GOLD     ASSAYING 


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GOLD   ASSAYING 

A    PRACTICAL    HANDBOOK 

GIVING  THE  MODUS  OPERANDI  FOR  THE  ACCURATE  ASSAY 

OF  AURIFEROUS  ORES  AND  BULLION 

AND     THE     CHEMICAL     TESTS     REQUIRED     IN 

THE  PROCESSES  OF  EXTRACTION  BY  AMALGAMATION 

CYANIDATION  AND  CHLORINATION 

WITH 

AN  APPENDIX  OF  TABLES  AND  STATISTICS 
BY 

H.  JOSHUA  ^HILLIPS,  F.I.C.,  F.C.S.,  ASSOC.INST.C.E. 

AUTHOR  OF  "  ENGINEERING  CHEMISTRY,"  ETC. 

WITH  NUMEROUS  ILLUSTRATIONS 


LONDON 

CROSBY    LOCKWOOD    AND    SON 

7,  STATIONERS'  HALL  COURT,  LUDGATE  HILL 
1904 

[All  rights  reserved] 


~":*HAL 


PRINTED  BY 

WILLIAM   CLOWES  AND  SONS,   LIMITED, 
LONDON   AND  BECCLES. 


PREFACE. 


THE  number  of  workers  interested  in  gold  mining,  metallurgy, 
and  assaying  has  been  largely  increased  in  recent  years  by  the 
exploitation  and  development  of  gold-bearing  deposits  in 
various  parts  of  the  world,  consequent  upon  the  perfection  of 
scientific  metallurgical  processes  for  the  extraction  of  the 
precious  metal  from  poor  and  complex  ores.  There  are  ex- 
cellent works  published  on  Mining  and  Metallurgy,  in  which  a 
chapter  or  so  is  devoted  to  Gold  Assaying,  but  in  many  cases 
the  subject  is  not  treated  in  sufficient  detail,  or  the  volume  is 
too  expensive  for  a  great  number  of  the  persons  interested  in 
the  subject.  The  writer  has  no  doubt,  therefore,  that  the  publi- 
cation of  a  small  work,  exclusively  dealing  with  the  subject  of 
Gold  Assaying,  is  warranted.  This  view  is  borne  out  by  his 
experience  of  the  requirements  of  the  numerous  prospectors, 
mining  engineers,  and  students  with  whom  he  has  come  in 
contact,  more  especially  in  a  recent  professional  visit  to  the 
Western  Australian  gold-fields.  He  trusts  that  this  little  book 
will  meet  those  requirements  and  earn  for  itself  the  appro- 
bation of  those  for  whom  it  has  been  compiled. 

The  writer  begs  to  acknowledge  his  obligations  to  various 
standard  works,  including  the  two  books  of  Rose  and  Eissler 
on  the  "  Metallurgy  of  Gold,"  and  the  two  manuals  of  Beringer 

a  3 

133490 


vi  PREFACE. 

and  Mitchell  dealing  with  "  Assaying,"  to  which  the  reader 
who  desires  to  follow  up  the  subject  may  be  referred.  He 
is  indebted  also  for  various  matters  of  information  to  the 
Journal  of  the  Board  of  Trade  and  the  Reports  of  the  Deputy- 
Master  of  the  Mint.  Thanks  are  due  to  Messrs.  Oertling, 
Townson  and  Mercer,  John  J.  Griffin  and  Sons,  and  the 
Morgan  Crucible  Company,  of  London,  for  kindly  allowing 
the  use  of  electros  for  illustrations. 

The  tabular  and  statistical  matter  given  in  the  Appendix 
has  been  compiled  from  various  sources,  and  mention  may 
be  made  here  of  "  The  Encyclopaedia  Britannica,"  "  West 
Australian  Geological  Survey  Bulletins,"  "Journal  of  the 
Board  of  Trade,"  "Reports  of  the  Deputy  Master  of  the 
Mint,  1902,"  and  the  writer's  own  work  on  "Engineering 
Chemistry." 

H.  J.  P. 


ROYAL  COLONIAL  INSTITUTE, 
LONDON. 

January ',  1904. 


CONTENTS. 


PAGE 

INTRODUCTION  i 


NATURAL  OCCURRENCE  AND  FORMS  OF  GOLD  3 

Flake  Gold        .  3 

Mustard  Gold 4 

Rough,  or  Coarse,  Gold     .                         ....  4 

Dendritic  Gold 4 

Crystalline  Gold                                                           .        .  4 

Sponge  Gold      ....                         ...  4 

Rhodic  Gold 4 

Free,  or  Visible,  Gold 4 

Gold  in  Iron  and  Copper  Pyrites 7 

Telluride  Ores  of  Gold 7 

Origin  of  Gold  Deposits 9 

PHYSICAL   CHARACTERS    OF   GOLD.                         .  u 

Occlusion  of  Gas  by  Gold 12 

CHEMICAL   PROPERTIES    OF   GOLD.        ...  13 

Alloys  of  Gold 13 

Gold  and  Copper 14 

Amalgams          .........  14 


viii  CONTENTS. 

PAGE 

CHEMICAL   PROPERTIES    OF    GOLD— (continued} 

Oxides  of  Gold 15 

Chlorides  of  Gold       ...  1 5 

Bromides  of  Gold 16 

Cyanides  of  Gold 16 

Purple  of  Cassius       ....                  ...  17 

Fulminate  of  Gold 17 

Preparation  of  Pure  Gold 17 

Chemical  Tests  for  Gold  . 1 8 

SAMPLING   OF   GOLD    ORE 20 

Crushing  and  grinding  the  Sample 22 

Mortars 23 

Bucking-plate  and  Hammer 27 

Calkins'  Combined  Radial  Bucking-plate  and  Hammer  .  27 

Quartering         .........  29 

Preparing  the  Powdered  Sample  for  Assay      ...  30 

FUSION .  34 

The  Assay  Furnace 35 

CUPELLATION 39 

Cupellation  of  the  Lead  Button 48 

Weighing  the  Button 49 

PARTING 53 

SCORIFICATION 56 

ASSAY   OF   BULLION 59 

Expressing  the  Gold  Value 59 

Process  of  Assay 61 

Preparation  and  Weighing  of  Assay  Piece        ...  62 

Determination  of  Gold  by  Wet  Assay       ....  68 

Valuation  of  Gold  sent  to  the  Mint  .  60 


CONTENTS.  ix 

PAGE 

ASSAY   OF  BULLION— (continued) 

Assay  of  Minute  Quantities  of  Gold  by  the  Microscope  .  69 
Estimation  of  Proportion  of  Gold  in  Quartz  from  the 

Specific  Gravity 71 

ASSAYS  IN  CYANIDATION,  CHLORINATION,  AND 

AMALGAMATION  PROCESSES    .                         .  73 

CYANIDATION— Synopsis  of  Process        ....  73 

Tests  necessary  in  Cyanidation 73 

Acidity  of  Gold  Ores 74 

Extraction  Tests 75 

Determination  of  Gold  in  Solution    .....  76 

Determination  of  the  Consumption  of  Potassium  Cyanide  76 

Testing  the  Strength  of  Cyanide  Solutions       ...  78 

Tank  Capacities        ....                         .        .  78 

Extraction  Test  for  Slimes        ...  -79 

CHLORINATION — Synopsis  of  Process      .        .        .        .81 

Chlorination  Assay 81 

AMALGAMATION — Synopsis  of  Process    .                        .  83 

Amalgamation  Assay        ...                         .        .  83 


APPENDIX. 

The  Imperial  Coinage 89 

Money  of  Foreign  Countries  in  which  the  French  Metric 

System  is  in  use     ........  93 

Weights,  Measures,  and  Money  of  Greater  Britain  .  .  102 

Weights,  Measures,  and  Money  of  the  United  States  .  .  105 
Foreign  Countries,  each  having  its  own  System  of  Money, 

Weights,  and  Measures 105 

Tables  of  Exchange 112 

Royal  Mint  Statistics .  114 

Yields  of  Gold  from  British  Possessions 117 


x  CONTENTS. 

PAGE 

Rand  Gold  Outputs 118 

Returns  from  Australian  Mints        ...  .         .     118 

Estimated  Production  of  Gold  in  Australasia  .        .  .122 

Gold  at  Indian  Mints 123 

Summary  of  the  Coinages  of  the  World,  1902          .  .124 

English  Weights  and  Measures 126 

Weights  and  Measures  of  the  British  Pharmacopoeia  of  1867  129 
Weights  and  Measures  of  the  Metrical  System  .  .  .129 
Tables  for  Conversion  of  Metrical  and  English  Measures  .  130 
Symbols  and  Atomic  Weights  of  the  Elements  .  .  .132 


INDEX    .  135 


LIST  OF   ILLUSTRATIONS. 


FIG.  PAGE 

1.  Braun  ore-sample  crusher  and  pulverizer        .         .  21 

2.  Braun  ore-sample  crusher,  in  section      ...  22 

3.  Geologist's  hammers 23 

4.  Iron  mortars  and  pestles          24 

5.  Agate  mortar  and  pestle 25 

6.  Calkins'  gyratory  mortar 25 

7.  Calkins'  gyratory  mortar,  in  section  and  detail       .  26 

8.  Bucking-plate  and  hammer 27 

9.  Calkins'     combined    radial     bucking-plate    and 

hammer       ........  28 

10.  Calkins'    combined     radial     bucking-plate     and 

hammer,  in  section 28 

n.  Clarksons' laboratory  divider 30 

12, 13.  Sieves .        .  31 

14.  Spatula 32 

15,  16,  17.  Pulp  balances 32 

18.  Weights 33 

19.  Forceps •         •  33 

20.  Fire-clay  crucible 34 

21.  Fire-clay  roasting  dish 34 

22, 23, 24.  Crucible  tongs                  . »    .                 •        •        •  35 

25.  Assay  furnace  (gas)                                                  .  36 

26.  Assay  furnace  (charcoal)                                   .        .  36 

27.  Assay  furnace  (oil) 37 

28.  Ingot  mould     ....                         .        .  38 

29.  Cupel        . 40 

30.  Cupel  mould  (Mint)                                         .        .  40 


Xll  LIST   OF   ILLUSTRATIONS. 


FIG. 


31.  Quadruple  mould  used  at  Royal  Mint  .         .         .         .40 

32.  Calkins' automatic  cupel  machine         .         .         .        .      41 

33.  Fire-clay  muffle 41 

34,  35.  Muffle  furnace  (Mint) 42 

36.  Prospector's  muffle  furnace  .         .         .        .         .      43 

37.  Morgan's  muffle  furnace  (charcoal)       ....      44 

38.  Fletcher's  muffle  furnace  (gas)      .  .         .      45 

39.  Nelson's  muffle  furnace  (oil) 46 

40.  Prospector's  set  of  apparatus 47 

41.  Cupel  tongs -48 

42.  Oertling's  assay  balance        ...  49 

43.  Assay  weights 50 

44.  Portable  assay  balance  for  prospectors  .       51 

45.  Steel  anvil     ....  54 

46.  Metallurgical  hammer  .  .         .       54 

47.  Porcelain  crucible  .  -54 

48.  Wash-bottle  ....  -54 

49.  Scorifier         ...  .         .  56 

50.  Scorifying  tongs     .  ...       56 

51.  Cornet  rolls    .  62 

52.  Shears -63 

53.  Gold  button  and  cornets       .  -64 

54.  Assay  flasks 65 

55.  Walker's  specific  gravity  balance  ...       72 

56.  Cyanide  assay  apparatus 75 

57.  Graduated  flask     ....  ...       77 

58.  Cyanide  test  flask          .  ...      77 

59.  Graduated  burette         ....  -77 

60.  Cyanide  test  apparatus  for  slimes  ...      80 

61.  Chlorination  assay  apparatus 82 

62.  Amalgamation  assay  apparatus 84 


GOLD    ASSAYING. 


INTRODUCTION. 

BY  assaying  is  generally  meant  the  scientific  determination  of 
one  or  more  elements  in  a  given  substance  by  means  of  dry 
reagents  and  heat,  in  contradistinction  to  analysis,  which  process 
determines,  by  chemical  wet  methods,  the  proportion  of  any 
desired  substance  contained  in  a  sample;  although  the  deter- 
mination of  certain  metals  by  wet  methods,  notably  iron  and 
copper,  are  characterized  as  wet  assays,  as  opposed  to  dry  or 
fire  assays.  In  this  little  work — which,  however,  only  concerns 
itself  with  gold,  and  incidentally  silver — both  systems  are  dealt 
with.  The  intrinsic  value  of  a  gold-bearing  mineral  or  alloy 
-(bullion)  of  course  depends  upon  the  amount  of  the  noble 
metal  it  contains,  and  a  means  of  its  accurate  determination  is 
an  indispensable  essential  in  the  metallurgy  of  gold,  and  in 
trade  dealings  in  the  metal. 

The  amount  of  gold  determined  in  minerals  is  expressed  in 
England  in  terms  of  ounces,  pennyweights,  and  grains  (troy) 
per  ton  of  2240  Ibs.  (long  toti),  and  in  America  per  ton  of  2000 
Ibs.  (short  toil]. 

Jewellers  in  this  country  express  the  proportion  of  gold  in 
an  alloy  in  carats,  i.e.  so  many  parts  of  gold  in  twenty-four 
parts.  The  French  decimal  system  is  now  also  much  in  vogue  : 
this  expresses  the  proportion  of  fine  gold  in  1000  parts  of  alloy. 

Before  entering  upon  the  actual  modus  operandi  of  gold 
assays,  some  account  of  the  mode  of  occurrence  and  of  the 

B 


2  GOLD   ASSAYING. 

physical  and  chemical  characteristics  of  the  precious  metal  will 
be  given. 

The  attractive  lustre,  beautiful  colour,  and  sparse  distribution 
of  gold  have  from  remote  ages  to  the  present  time  made  the 
metal  highly  prized  and  much  sought  after  by  all  nations  of  the 
world.  The  word  gold  is  doubtless  associated  with  the  Sanscrit 
jvalita,  derived  from  the  verb  j'val^  "  to  shine."  Gold  as  an 
element  is  the  only  metal  which  has  a  yellow  colour  when  in 
mass,  although  under  various  conditions  the  colour  is  modified  ; 
for  instance,  gold  leaf  is  translucent,  and  by  transmitted  light 
appears  green,  but  maintains  its  natural  yellow  colour  by 
reflected  light. 

Menes,  who  reigned  in  Egypt  B.C.  3600,  alludes  in  his  codes 
to  the  intrinsic  value  of  the  precious  metal,  and,  doubtless 
long  before  his  time,  in  prehistoric  ages,  the  natives  of  India 
and  China  were  acquainted  with  its  virtues.  Prior  to  the 
discovery  of  America  by  Columbus,  practically  all  the  gold 
was  derived  from  India.  Doubtless  from  the  fact  that  gold 
occurs  in  the  metallic  state  in  alluvial  sands,  it  was  the  first 
element  and  metal  that  was  isolated  and  used  as  such. 


NATURAL  OCCURRENCE  AND  FORMS  OF 
GOLD. 

GOLD,  as  found  in  nature,  is  generally  in  the  metallic  state, 
and  occurs  in  various  parts  of  the  globe  :  (i)  in  siliceous  or 
quartz  veins  t  filling  wp  fissures  of  thte  earth's  crust;  and  (2)  in 
placers  or  alluvial  deposits  left  by  streams  that  have  disinte- 
grated rocks  containing  the  auriferous  veins. 

Gold  is  rarely  found  absolutely  pure  in  nature,  silver  being 
the  most  common  impurity,  while  it  is  also  associated,  either 
in  a  fine  state  of  mechanical  mixture,  or  in  some  instances 
in  chemical  combination,  in  iron  pyrites,  copper pyrites ;  nagyagite 
(telluride  combination),  magnet 'tie,  iridosmine,  galena,  blende, 
tetradymite,  zircon,  garnets,  rutile  and  barytes,  wolfram,  and 
scJieelite.  In  Western  Australia  it  occurs  free  and  in  com- 
bination with  tellurium  and  lead  and  iron  pyrites  in  a  matrix 
of  quartz,  and  the  carbonates  of  lime  and  magnesia  and  kaolin. 
There  are  numerous  other  minerals  in  which  gold  occurs  in 
small  quantities,  and  the  ores  of  silver,  antimony,  and  bismuth 
appear  to  always  contain  the  metal.  Gold  also  occurs  in  sea 
water  in  combination  with  chlorine,  bromine,  or  iodine,  to  the 
extent  of  J  grain  to  i  grain  per  ton. 

There  are  several  terms  given  to  native  gold,  depending 
upon  the  outward  form  in  which  it  is  naturally  found ;  thus — 

Flake  Gold. — This  variety  is  generally  found  on  the  faces 
of  foliation  and  cleavage  planes  of  the  mineral  in  which  it  is 
contained,  generally  in  kaolin  and  diabase  schists.  It  is  exceed- 
ingly thin,  and  floats  on  water,  and  very  little  of  it  can  be 
extracted  from  its  matrix  by  ordinary  battery  treatment. 


4  GOLD   ASSAYING. 

Mustard  Gold  is  a  form  of  the  noble  metal  in  an 
extremely  fine  yellow  powder,  contained  in  microscopic  fissures 
of  its  matrix,  and  doubtless  produced  by  the  decomposition  of 
highly  auriferous  sulphides  and  tellurides. 

Rough,  or  Coarse,  Gold. — This  is  the  usual  form  in  which 
gold  occurs  in  reefs,  being  irregular  in  form  and  having  no 
specific  dimensions. 

Dendritic  Gold  is  a  beautiful  fern-like  form  of  the  metal, 
incipiently  crystallized  in  cleavages. 

Crystalline  Gold. — Crystals,  in  the  form  of  single  octa- 
hedrons, have  been  found  in  asbolite — a  double  oxide  of  man- 
ganese and  cobalt — in  a  kaolin  clay  locally  known  as  "  pug," 
in  Kanowna,  Western  Australia. 

Sponge'^Gold. — This  form  of  gold  has  been  found  in 
beautiful  masses  on  the  oxidized  zones  of  the  Kalgoorlie  Mines, 
where  at  certain  depths  tellurides  of  the  noble  metal  are  found. 
In  structure  it  is  very  much  akin  to  the  ordinary  marine 
sponge,  consisting  of  irregular  strings  and  cellular  masses  of 
brilliant  gold,  which  form  has  doubtless  been  produced  by  the 
oxidation  and  removal  of  the  tellurium  with  which  it  was 
originally  combined.  In  March,  1897,  one  piece  of  sponge 
gold  weighing  60  ozs.  was  taken  from  the  2oo-feet  level  of  the 
Great  Boulder  Mine,  West  Australia. 

Rhodic  Gold. — This  combination  is  found  in  Mexico, 
and  has  a  golden  colour,  and  contains  from  34  to  43  per  cent. 
of  rhodium. 

Free,  or  Visible,  Gold. — In  quartzose  rock  and  alluvial 
sands  gold  may  either  be  disseminated  in  a  finely  divided  state 
throughout  the  matrix,  or  in  small  grains  or  scales,  or  in  pieces 
of  substantial  weight  unevenly  distributed.  These  pieces  are 
usually  termed  nuggets,  and  occasionally  are  found  of  such  a 


NATURAL  OCCURRENCE  AND  FORMS  OF  GOLD.   5 


size  as  to  be  worth  thousands  of  pounds  sterling ;  as,  for 
instance,  the  "Welcome"  nugget,  found  in  the  Colony  of 
Victoria,  which  weighed  no  less  than  2195  ozs.,  or  183  Ibs., 
and  which,  after  refining,  was  worth  ^8376  IQS.  6d.  In  1842 
a  lump  of  gold  was  discovered  at  Miask,  Russia,  weighing 
96  Ibs. ;.  and  the  "Blanch  Barkley"  nugget  found  in  South 
Australia  weighed  146  Ibs. 

As  previously  stated,  the  free  or  metallic  gold  is  always 
associated  with  impurities,  the  nature  and  extent  of  which  will 
be  seen  from  the  following  analyses  of  native  gold  from  various 
parts  of  the  world.  The  purest  gold  as  yet  found  occurs  in 
the  Mount  Morgan  Mine,  Queensland,  Australia,  and  contains 
99*7  per  cent,  of  the  metal. 

According  to  the  Report  of  the  United  States  Census,  1880, 
the  average  composition  of  placer  gold  obtained  from  the  chief 
producing  States  of  America  was — 


y 


State. 

Gold. 

Silver. 

Base  metals. 

California    .... 
Idaho           .... 
Montana      .... 
Oregon        .... 

Per  cent. 
8836 
78-06 

89-5I 
87-27 

Per  cent. 
11-24 
21-34 

io'O9 
12-33 

Per  cent. 
0*40 

o'6o 

O'4O 
0-40 

GOLD  FROM  SIBERIA  (ROSE). 


Schobrowski, 
near 
Katherinenburg. 

Katherinenburg. 

Perroc 
Powlowsk. 

Per  cent. 

Per  cent. 

Per  cent. 

Gold  
Silver          .... 

98-76 
o-i6 

93'34 
6-28 

92-60 
7-08 

Copper        .... 

0'3S 

0'06 

0-18 

Iron   ..... 

0-05 

0-32 

0'06 

6 


GOLD   ASSAYING. 


NATIVE  GOLD  FROM  CENTRAL  AMERICA. 


Malapso. 

Trinidad. 

Guano. 

Santa  Rosa. 

Gold     . 
Silver  . 

Per  cent. 
88-24 
1176 

Per  cent. 
82-40 
17-60 

Per  cent. 

73-68 
26-32 

Per  cent. 
64'93 

35  '07 

1  00  '00 

lOO'OO 

lOO'OO 

lOO'OO 

GOLD  FROM  WALES. 


Mawdoc  River. 

St.  David's. 

Dolgelly. 

Gold  
Silver          .... 

Per  cent. 
89-85 

io'i5 

Per  cent. 
90-85 

9'i5 

Per  cent. 
95*55 
4'45 

1  00  '00 

lOO'OO 

lOO'OO 

The  following  table  shows  the  composition  of  native  gold 
found  in  the  West  Australian  gold-fields  :  * — 


No. 

Nature  of  gold. 

Locality. 

Sp.  gr. 

Gold. 

Silver. 

Copper 
and  iron. 

Per  cent. 

Per  cent. 

Per  cent. 

I 

Small  alluvial  nuggets 

Hall's   Creek,  Kim- 

16-62 

93'30 

6-60 

O'lO 

berley 

2 

3-02.  alluvial  nugget 

Ditto 

16-80 

88-39 

11*61 

— 

3 

"  Bobby      Dazzler  " 

Shark's    Gully,    Pil- 

14-66 

76-81 

23-04 

OT5 

nugget 

barra 

4 

From  quartz  boulders 

Taiga,  Pilbarra 

16-20 

84-46 

15*54 

— 

5 

Gold  from  conglome- 

Nullagine, Pilbarra 

— 

91-21 

8-79 

— 

rate 

6 

Gold  from  quartz  reef 

Bamboo  Creek,  Pil- 

— 

94-00 

6"oo 

— 

barra 

7 

55                  55                   55 

Towranna,  Pilbarra 

— 

94'53 

5'47 

— 

8 

J>                 55                    55 

Peak  Hill 

17-16 

96-54 

3'46 

— 

9 

5>                   55                   55 

Nannine  Murchison 

1575 

89-45 

10-50 

— 

10 

Sponge    gold    from 

Kalgoorlie 

99-91 

o"C9 

— 

lode 

ii 

Coarse     gold     from 

Block  50,  Coolgardie 

18-91 

99-46 

0-64 

Trace 

ironstone  pebbles 

12 

Crystalline  gold  from 

Red  Hill,  Coolgardie 

18-00 

93-21 

6-72 

— 

calcite  vein 

!3 

Alluvial  . 

Preston  River 

— 

92-90 

7-10 

— 

H 

Quartz  reef  electrum 

Donnybrook 

— 

49-29 

5071 

Vide  Western  Australian  Geological  Survey  Bulletin,  No.  6,  1902. 


NATURAL  OCCURRENCE  AND   FORMS   OF  GOLD.       7 

The  average  value  of  gold  won  in  Western  Australia  for 
1900  was  ^3741  per  ounce. 

Gold  in  Iron  and  Copper  Pyrites. — There  appears 
to  be  a  difference  of  opinion  as  to  whether  the  gold  is  in  actual 
combination  with  the  sulphur  or  iron  contained  in  pyrites,  or 
in  a  state  of  fine  mechanical  comminuted  condition  in  the 
mineral;  but  from  recent  researches  on  very  finely  divided 
auriferous  pyrites,  by  the  action  of  cyanide  of  potassium  and 
microscopic  observations,  it  is  generally  held  that  the  gold  is 
not  actually  combined  with  the  sulphur,  but  merely  locked  up  in 
the  crystals  in  the  metallic  state. 

The  amount  of  gold  in  pyritic  ore  varies  considerably  from 
a  few  grains  to  many  ounces  per  ton ;  a  good  average  working 
ore  containing  about  i  oz.  of  the  precious  metal  per  ton. 

Telluride  Ores  of  Gold. — In  these  ores  the  gold  is  in 
actual  chemical  combination — occurring  for  the  most  part  in 
Colorado,  California,  West  Australia,  and  Hungary. 

Calaverite  is  found  in  Colorado,  and  the  pure  mineral  con- 
tains 44*5  per  cent,  of  gold  and  55*5  per  cent,  of  tellurium, 
corresponding  to  the  formula  AuTe2. 

Graphic  tellurium,  or  sylvanite,  is  a  mineral  found  to  corre- 
spond to  the  formula  (AuAg)Te3,  found  also  in  various  parts 
of  America. 

Nagyagite,  or  foliated  tellurium,  found  in  Transylvania, 
contains — 

Gold 9'0  to  13-0  per  cent. 

Lead 54'O  per  cent. 

Tellurium 32*2        ,, 

and  also  occasionally  contains,  in  addition,  silver,  sulphur,  and 
copper. 

In  recent  years  a  number  of  telluride  lodes  have  been 
discovered  in  the  West  Australian  gold-fields,  which  have 
greatly  added  to  the  mineral  wealth  of  that  colony.  The 
following  is  an  analysis,  by  the  writer,  of  such  an  ore  found 
in  the  mines  of  the  Lake  View  Consols,  in  Kalgoorlie — • 


GOLD   ASSAYING. 


Iron          ........ 

Sulphur    ........ 

Silica        ........ 

Alumina  ........ 

Lime         ........ 

Magnesia  ....... 

Lead 

Copper     .         .         .         .         .         .         .         . 

Arsenic     ........ 

Carbonic  acid,  oxygen,  gold,  silver,  and  tellurium 


Per  cent. 

IS^S 

4-50 

42-50 

6-12 

8-35 

5^5 

0*06 

O'I2 

0-05 

17-40 

1 00 'DO 


Gold 

Silver 

Tellurium 


Per  ton. 

ozs.  dwts.  grs. 

4112 

o     14    10 

32      10         2 


Adolphe  Carnot'*  has  made  a  complete  analysis  of  the 
telluride  ore  from  Lake  View  Consols  and  the  Great  Boulder 
Proprietary  mines  in  West  Australia,  and  in  addition  to  the 
presence  of  calaverite  and  sylvanite^  he  has  isolated  two  com- 
pounds of  telluride  containing  mercury,  the  one  he  terms 
kalgoorlite,  having  the  formula  (AuAgHg)2Te,  and  a  sesqui- 
telluride,  coolgardite  (AuAgHg)2Te3. 

The  following  are  analyses  of  some  typical  gold-telluride 
compounds  found  in  the  Kalgoorlie  mines  : — 


• 

Sylvanite 
(Krusch). 

Petzite 
(Carnot). 

Coolgardite 
(Phillips). 

Kalgoorlite 
(Mingaye). 

Kalgoorlite 
(Carnot). 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Gold  . 

28-55 

24*16 

38-II 

20-72 

26-10 

Silver 

9-76 

41-22 

3'95 

30-98 

3°'43 

Mercury 

2-00 

3'80 

10-86 

070 

Copper 

0-32 

O'lO 

0-95 

0-05 

0'60 

Iron  . 

O'o6 

— 

0-85 

— 

0-40 

Nickel 

O'lO 

— 

— 

— 

Tellurium 

60-83 

32-33 

50-75 

37-26 

41-11 

Selenium 

O'2O 

— 

— 

Antimony 

— 

— 

1-50 

— 

0'8o 

Sulphur 

0-09 

— 

0-13 

— 

99-9I 

99'8l 

99-91 

lOO'OO 

100-14 

Vide  Compt.  Rend.,  1901,  132,  1298-1302 


ORIGIN   OF   GOLD   DEPOSITS. 


The  following  is  also  an  analysis  of  a  complex  gold- 
bearing  compound  found  in  Kalgoorlie,  and  termed  enargite 
(Krusch)  :— 


Per  cent. 
O'26 
0'12 
0'22 

41-69 
476 


O'lO 

16-87 
4*30 

0*05 

28-43 


Gangue 

Gold 

Silver. 

Copper 

Iron 

Nickel 

Zinc 

Lead 

Arsenic 

Antimony 

Tellurium 

Sulphur    . 


Origin  of  Gold  Deposits. — Geologists  differ  somewhat 
as  to  the  origin  of  the  lodes  or  veins  in  which  gold  is  found, 
but  the  theory  now  generally  accepted  is  that  the  fissures 
produced  upon  the  gradual  cooling  down  of  the  earth  in 
prehistoric  times  were  filled  with  the  mineral  they  now  contain 
by  precipitation  from  aqueous  solution.  How  gold  came  to  be 
present  in  such  mineral  is  somewhat  hypothetical.  Professor 
Whitney  is  of  opinion  that  it  was  deposited  simultaneously 
from  the  solutions  from  which  the  lodes  or  veins  were  pre- 
cipitated ;  and  this  appears  the  more  evident  from  the  presence 
of  the  precious  metal  in  pyrites  enclosed  in  siliceous  incrusta- 
tions. The  invariable  presence  of  gold  in  the  iron  pyrites 
contained  in  lodes  has  naturally  suggested  the  idea  that  the 
sulphide  of  iron  is  an  essential  factor  as  to  the  presence  of 
gold  in  its  association  with  silica,  and  when  it  is  considered 
that  iron  pyrites  have  been  found  to  be  produced  from  a 
solution  of  iron  sulphate  by  reducing  agents,  and  consequently 
if  during  such  reduction  gold  was  present  in  solution,  it  would 
doubtless  be  co-precipitated  with  the  crystals.  This  is  a  very 
probable  theory. 

At  a  recent   meeting   of  the   Institution  of    Mining  and 
Metallurgy  held  in  London,  Mr.  B.  H.  Bennetts  read  a  paper, 


IO  GOLD  ASSAYING. 

in  which  he  described  a  curious  occurrence  of  gold  at  the 
Mount  Lyell  mine,  Tasmania,  singularly  demonstrating  the 
manner  in  which  gold  migrates  in  solution,  and  hence  is 
deposited  as  metal,  maybe  far  removed  from  its  original 
source.  "  A  piece  of  wrought-iron  was  picked  up  by  the  fore- 
man of  the  mine  (it  originally  formed  a  part  of  a  mine  truck) 
from  the  gutter  that  carried  away  the  water  from  the  mine 
tunnel.  It  displayed  a  deposit  of  copper,  but  on  removing 
this,  the  iron  in  places  displayed  a  deposit  of  metallic  gold. 
The  gold  was  not  uniformly  distributed,  but  appeared  in  plates 
especially  near  three  bolt-holes.  The  deposit,  of  a  beautiful 
yellow  colour,  responded  to  the  usual  tests  for  gold.  Here  is, 
doubtless,  an  instance  in  which  an  aqueous  acid  solution,  con- 
taining a  minute  proportion  of  gold  in  solution,  in  addition  to 
copper,  coming  into  contact  with  a  reducing  agent  (iron), 
precipitated  copper,  and  this  copper-iron  couple,  generating 
sufficient  electricity  in  the  acid  solution,  precipitated  the  gold 
in  a  bright  metallic  form." 


PHYSICAL   CHARACTERS   OP   GOLD. 

GOLD  has  a  beautiful  rich  yellow  colour  and  a  high  metallic 
lustre.  When  pure  it  is  nearly  as  soft  as  lead,  and  on  this 
account  it  is  hardened  with  silver,  copper,  etc.,  when  required 
to  be  used  for  coinage  and  jewellery. 

The  metal  has  remarkable  degrees  of  malleability  and 
ductility ;  more  than  those  possessed  by  other  metals  and  at 
all  temperatures.  A  single  grain  of  gold  can  be  drawn  into  a 
wire  over  500  feet  long,  and  can  be  beaten  out  to  -^^ w  of 
an  inch  in  thickness,  which  may  be  further  reduced  by  treat- 
ment with  a  dilute  solution  of  cyanide  of  potassium.  Thus 
300,000  of  such  leaves  laid  upon  each  other  would  be  only 
one  inch  thick,  yet  each  leaf  may  be  beaten  so  perfect  and  free 
from  holes  that  one  of  them  laid  upon  any  surface  gives  the 
appearance  of  solid  gold.  They  are  so  thin  that  if  formed  into 
a  book  1500  would  only  occupy  the  space  of  a  single  leaf  of 
common  paper,  and  an  octavo  volume  of  an  inch  thick  would 
have  as  many  pages  as  the  books  of  a  well-stocked  library  of 
1500  volumes  of  200  pages  each.  Pure  gold  has  a  tenacity 
of  7  tons  per  square  inch,  with  an  elongation  of  30*8  per 
cent.  The  presence,  however,  of  minute  quantities  of  other 
elements,  such  as  tellurium,  bismuth,  and  lead,  materially 
affects  its  physical  properties.  The  specif  c  gravity  of  cast  gold 
varies  from  19-29  to  19*37,  and  pure  precipitated  gold  has  a 
density  of  2072.  Its  melting  point ',  as  determined  by  various 
observers,  varies  from  1037°  to  1072°  C,  and  it  boils  at  about 
2240°  C. 

At  temperatures  below  its  melting  point  gold  can  be  welded 
like  iron,  and  precipitated  gold  can  be  consolidated  under 


12  GOLD  ASSAYING. 

pressure.  It  cannot  be  well  employed  for  castings,  since  the 
metal  contracts  materially  upon  solidification.  The  coefficient  of 
lineal  expansion  of  gold  is  0*0000144  between  o°  and  100°  C. 
As  compared  with  silver  at  100,  its  electrical  and  thermal  con- 
ductivities are  76*7  and  60  respectively.  The  atomic  weight  of 
gold  is  196*85  compared  with  hydrogen,  while  its  atomic  volume 
is  10*2,  the  latent  heat  being  i6'3.  Taking  iron  as  100,  the 
specific  magnetism  of  gold  is  3*47-  Gold  crystallizes  in  the 
cubic  system. 

OCCLUSION    OF   GAS   BY   GOLD. 

Gold  is  capable  of  occluding  0-48  of  its  volume  of  hydro- 
gen, and  o'2o  of  its  volume  of  nitrogen.  "  Cornets"  from  the 
assay  of  gold  may  retain  gas  if  they  are  not  strongly  heated. 


CHEMICAL   PROPERTIES    OP   GOLD. 

GOLD  undergoes  no  change  by  the  action  of  the  atmosphere 
and  moisture  at  any  temperature,  and,  with  the  exception  of 
selenic  acid,  no  single  acid  has  practically  any  effect  upon  it. 
It  dissolves,  however,  in  aqua  regia — a  mixtiwe  of  hydro- 
chloric and  nitric  acids — forming  gold  trichloride  (AuCl3),  and 
also  in  solutions  containing  free  chlorine  and  bromine  and 
alkaline  cyanides.  Strong  sulphuric  acid,  and  polysulphides  of 
the  alkaline  metals,  also  dissolve  finely  divided  gold. 

Alloys  of  Gold. — Gold  can  be  made  to  combine  with  most 
other  metals,  the  more  important  combinations  being  those 
with  silver  and  copper,  and  with  these  elements  it  unites  in  all 
proportions. 

The  gold-silver  alloys  are  characterized  by  being  more 
fusible,  elastic,  and  harder  than  either  free  metal,  while  the  colour 
of  gold  is  materially  lightened  by  the  addition  of  silver.  There 
have  been  several  true  crystallizable  compounds  of  silver  and 
gold  isolated,  corresponding  to  the  formulae  AuAg,  AuAg2, 
Au8Ag,  Au6Ag,  and  Au2Ag.  Silver-gold  alloys  used  by  jewellers 
are  :  green  gold,  containing  25  per  cent,  silver  and  75  per  cent, 
gold;  dead-leaf  gold,  containing  30  per  cent,  silver  and  70  per 
cent.  gold.  Electrum  is  a  term  used  to  designate  the  pale 
yellow  alloys  containing  from  15  to  35  per  cent,  of  silver. 
Triple  compounds  of  silver,  copper,  and  gold  are  mostly  used 
by  British  jewellers,  containing  gold  parts  in  every  24  (carats)  : 
22,  18,  15,  12,  and  9  respectively. 

Sulphuric  and  nitric  acids  act  upon  silver-gold  alloys,  dis- 
solving out  the  silver,  and  leaving  the  gold,  if  the  silver  present 


14  GOLD  ASSAYING. 

is  over  60  per  cent. ;  but  if  under  this  amount,  some  silver  will 
remain  undissolved. 

Gold  and  Copper. — Like  silver,  copper  unites  with 
gold  in  all  proportions,  forming  alloys  of  a  reddish  colour, 
which  are  less  malleable,  more  elastic  and  fusible,  and  harder 
than  gold.  British  standard  gold  is  a  gold-copper  alloy,  which 
has  been  used  for  our  coinage  since  1526,  and  contains  eleven- 
twelfths  gold  and  one-twelfth  copper,  or,  in  other  words, 
916*6  fate  (i.e.  parts  gold  per  1000),  or  22  carats  (i.e.  gold  in 
twenty-four  parts);  or  copper  8*33  per  cent,  and  gold  91*67 
per  cent.  The  English  standard  is  also  that  used  by  India, 
Russia,  Portugal,  and  Turkey.  France  and  America  and  many 
other  civilized  countries  use  the  900  standard  (i.e.  900  parts 
gold  per  1000,  and 'thus  containing  10  per  cent,  copper).  This 
standard  originated  in  France  in  the  year  1794.  In  addition 
to  the  copper,  most  gold  coinage  contains  from  0*8  to  1*2  per 
cent,  of  silver. 

Sulphuric  and  nitric  acids  dissolve  out  the  copper  from 
the  alloys  if  the  copper  present  be  more  than  6  per  cent.; 
otherwise  some  of  the  latter  remains  undissolved.  Aqua 
regia  completely  dissolves  the  copper-gold  alloys. 

Amalgams. — Mercury  combines  with  metals  in  various 
proportions,  and  these  are  termed  amalgams^  and  as  mercury 
is  extensively  employed  in  the  extraction  of  gold  from  its 
ores,  gold  amalgam  becomes  an  important  commercial  com- 
modity. Gold  is  dissolved  by  mercury  at  the  ordinary  tem- 
perature, forming  amalgams  which  are  solid,  liquid,  or  pasty, 
according  to  the  proportion  of  mercury  used.  The  amalgam 
containing  85  per  cent,  of  mercury  is  solid,  and  crystallizes  in 
yellowish-white  prisms;  that  containing  87  per  cent,  of  mercury 
is  pasty;  and  90  per  cent,  of  mercury  produces  a  liquid 
amalgam.  Gold  amalgam  is  soluble  in  excess  of  mercury, 
and  if  the  liquid  amalgam  thus  produced  is  subjected  to  slight 
pressure  in  a  filter  of  chamois  leather,  mercury  filters  through, 
leaving  behind  a  pasty  white  amalgam  containing  about  one- 
third  its  weight  in  gold.  Gold  amalgam  is  dissociated  below 
a  bright  red  heat,  the  mercury  distilling  and  leaving  the  gold. 


CHEMICAL   PROPERTIES   OF  GOLD.  15 

Oxides  of  Gold. — There  are  two  oxides  of  gold  known — 
the  suboxide  (Au.2O)  and  a  sesquioxide  (Au2O3),  otherwise  known 
as  aurous  oxide  and  auric  oxide.  Aurous  oxide  is  a  dark- 
green  powder,  produced  by  adding  a  dilute  solution  of  potassic 
hydrate  to  aurous  chloride  (AuCl).  It  is  somewhat  soluble  in 
excess  of  alkali.  Treatment  with  hydrochloric  acid  converts 
it  into  auric  chloride  (AuCl3)  and  metallic  gold.  The  auric 
oxide  is  produced  by  decomposing  a  solution  of  auric  chloride 
by  means  of  magnesia,  a  combination  of  the  oxide  and  magnesia 
is  precipitated,  and  on  removing  the  latter  with  diluted  nitric 
acid,  a  yellow  hydrate  or  brown  anhydrous  powder  of  the 
oxide  is  produced,  depending  upon  the  degree  of  dilution  of 
the  acid.  The  oxide  is  decomposed  by  sunlight,  and,  when 
subjected  to  a  temperature  of  about  245°  C.,  it  is  dissociated 
into  metallic  gold  and  oxygen  gas.  Auric  oxide  is  dissolved 
by  hydrochloric  acid,  forming  the  trichloride ;  and  is  also  dis- 
solved without  decomposition  by  nitric  and  sulphuric  acids. 
The  hydrated  oxide  forms  soluble  compounds  with  alkalies, 
called  aurateS)  and,  with  the  alkaline  earths,  insoluble  aurates. 

Chlorides  of  Gold. — The  chlorides  of  gold  are  the  most 
important  compounds  of  the  metal.  It  is  in  the  form  of 
chloride  that  gold  is  extracted  from  many  of  its  ores  by  what 
is  known  as  the  chlorination  process.  There  are  two  chlorides 
of  gold — the  aurous  chloride  (AuCl)  and  the  auric  chloride 
(AuCl3). 

The  aurous  chloride  is  produced  by  heating  auric  chloride  to 
about  175°  C.j  chlorine  is  expelled,  and  a  pale  yellow  powder 
of  AuCl  is  left,  and  if  the  temperature  be  increased  beyond 
200°  C.,  the  whole  of  the  chlorine  is  given  off  and  metallic 
gold  left.  It  is  decomposed  by  sunlight,  and,  when  deposited 
with  a  solution  of  potassic  hydrate,  it  yields  hydrated  aurous 
oxide  and  potassic  chloride. 

Auric  chloride,  or  perchloride  of  gold,  is  produced  by 
dissolving  gold  in  aqua  regia  (i  of  nitric  acid  to  2  of  hydro- 
chloric acid)  and  evaporating  to  dryness  at  a  temperature 
below  120°  C. ;  otherwise  it  decomposes.  The  AuCl3  remains 
as  a  red  deliquescent  mass,  containing  more  or  less  of  the 


1 6  GOLD   ASSAYING. 

protochloride  (AuCl).  It  is  freely  soluble  in  water,  alcohol, 
and  ether.  It  is  decomposed  by  light,  and  at  288°  C.  it  melts 
and  decomposes  into  gold  and  chlorine  gas.  Many  proto- 
salts,  such  as  ferrous  sulphate,  decompose  the  chloride  and 
precipitate  fine  metallic  gold.  Organic  matter  and  metals 
act  in  like  manner.  If  a  solution  of  AuCl3  be  filtered  through 
charcoal,  it  is  decomposed,  and  the  gold  remains  in  the 
charcoal,  which  can  be  obtained  when  the  latter  is  burnt  off. 
This  method  is  often  adopted  in  the  chlorination  process  of 
gold  extraction.  A  current  of  sulphurous  acid  gas  completely 
decomposes  a  solution  of  AuCl3,  precipitating  the  gold  as  a 
fine  brown  powder.  Alkaline  chlorides  form  double  salts 
with  the  compound,  as  2(KCl5AuCl3)5H2O.  It  also  forms 
double  salts  with  the  chlorides  of  most  of  the  organic  bases. 

Bromides  of  Gold. — There  being  now  a  bromide  process 
in  vogue  for  gold  extraction,  these  compounds  are  of  im- 
portance. There  are  two  bromides  of  gold — the  protobromide 
(AuBr)  and  the  tribromide  (AuBr3).  The  protobromide  is  a 
yellowish-green  powder,  and  is  produced  by  heating  the  tri- 
bromide to  140°  C.  It  is  decomposed  by  water  into  metallic 
gold  and  the  tribromide.  Heat  resolves  it  into  gold  and 
bromine,  which  is  eliminated  as  vapour.  The  tribromide  is 
produced  by  the  action  of  bromine  and  water  on  gold  at  a 
gentle  heat.  Its  properties  are  similar  to  those  of  the  tri- 
chloride. It  is  a  crystalline  salt,  deliquescent  and  soluble  in 
water,  forming  a  highly  coloured  solution  of  a  brownish  red 
colour.  The  salt  is  decomposed  in  a  similar  manner  to  the 
trichloride. 

Cyanides  of  Gold. — What  is  known  as  the  cyanide 
process  of  gold  extraction  has  made  the  cyanides  of  gold  and 
their  double  combinations  objects  of  much  interest.  There 
are  two  cyanides  of  gold — the  aurous  (AuCy)  and  the  auric 
(AuCy3) :  the  latter  has  not  yet  been  isolated  in  a  free  state, 
but  is  known  to  exist  in  combination  with  other  cyanides.  The 
aurous  cyanide  is  produced  by  heating  the  double  cyanide  of 
gold  and  potassium  (KAuCy2)  with  nitric  or  hydrochloric  acid. 
It  is  a  lemon-yellow  crystalline  powder,  unacted  upon  by  the 


CHEMICAL  PROPERTIES   OF  GOLD.  I/ 

atmosphere,  and  is  insoluble  in  water,  but  soluble  in  ammonia, 
alkaline  cyanides,  and  sodic  hyposulphite.  It  is  dissolved  by 
aqua  regia,  but  not  by  the  single  acids.  On  heating  with 
potassic  hydrate,  it  is  decomposed,  metallic  gold  being  pre- 
cipitated as  a  fine  powder.  Heating  decomposes  it,  with  the 
production  of  cyanogen  gas  and  metallic  gold. 

The  most  important  double  combination  of  auric  cyanide 
is  the  aurocyanide  of  potassium,  which  can  be  prepared  by 
dissolving  fine  gold  and  auric  oxide  or  aurous  cyanide  in  an 
aqueous  solution  of  potassic  cyanide,  from  which  it  may  be 
obtained  by  crystallization.  This  compound  is  slightly  soluble 
in  water,  and  articles  of  copper  and  silver  suspended  in  the  hot 
solution  are  gilded.  Unless  potassic  cyanide  be  in  excess, 
a  precipitate  of  gold  is  obtained  when  zinc  or  the  alkali  metals 
are  added  to  the  solution. 

Purple  of  Cassius. — This  purple  compound,  discovered 
by  Cassius  in  1683,  is  prepared  by  adding  a  dilute  solution  of 
a  mixture  of  stannous  and  stannic  chloride  to  a  dilute  solution 
of  chloride  of  gold.  It  is  also  formed  by  digesting  metallic 
tin  in  a  neutral  solution  of  chloride  of  gold,  metallic  gold  and 
purple  of  Cassius  being  formed.  It  is  this  compound  which 
gives  the  beautiful  red  colour  to  Bohemian  glass.  Purple  of 
Cassius,  when  mixed  with  borax  or  fusible  glass,  gives  to  the 
surface  of  china  a  beautiful  rose  or  purple  colour. 

Fulminate  of  Gold. — This  violently  explosive  com- 
pound of  oxide,  of  gold  and  ammonia  (Au2O3(NH3)4)  is  pre- 
pared by  adding  ammonium  hydrate  to  a  solution  of  chloride 
of  gold,  when  the  grey  precipitate  of  the  fulminate  is  produced. 
It  explodes  on  being  struck  or  by  being  heated  to  145°  C.  It 
is  soluble  in  potassic  cyanide,  but  is  insoluble  in  water. 
It  is  decomposed  by  protochloride  of  tin  and  sulphuretted 
hydrogen. 

There  are  many  other  less  important  compounds  of  gold, 
such  as  the  silicates,  hyposulphides,  sulphides,  etc.,  for  par- 
ticulars of  which  the  reader  is  referred  to  the  larger  chemical 
treatises. 

Preparation    of   Pure   Gold. — Pure  gold— or  "fine" 

c 


1 8  GOLD  ASSAYING. 

gold,  as  it  is  known  in  the  bullion  and  money  markets — which 
is  required  as  a  standard  in  the  assay  of  bullion,  is  prepared 
in  the  Royal  Mint  for  the  testing  of  the  British  gold  coinage 
as  follows  :  *  Gold  cornets,  obtained  by  the  usual  gold  assays, 
are  dissolved  in  nitre-hydrochloric  acid  (aqua  regia) ;  the  excess 
of  acid  is  evaporated  off  by  gentle  heat,  and  a  mixture  of 
alcohol  and  potassium  chloride  added  to  precipitate  any  trace 
of  the  metal  platinum  that  may  be  present.  The  whole  is  now 
diluted  with  distilled  water  in  the  proportion  of  about  -|  oz.  of 
gold  to  i  gallon  of  water ;  the  solution  is  stirred,  and  allowed 
to  stand  for  3  weeks.  At  the  end  of  this  time  all  traces  of 
silver  present  will  have  subsided  as  a  precipitate  of  insoluble 
chloride  (AgCl).  The  clear  yellow  solution  of  gold  chloride 
is  then  carefully  syphoned  off  into  a  glass  vessel.  Crystals  of 
pure  oxalic  acid  are  now  added  from  time  to  time,  and  the 
liquid  warmed  and  allowed  to  stand  for  2  or  3  days,  at  the  end 
of  which  time  the  whole  of  the  gold  will  be  precipitated  in  the 
form  of  spongy  scales.  The  gold  precipitate  is  then  washed 
by  decantation  repeatedly  with  hydrochloric  acid,  pure  water, 
and  ammonia  alternately,  and  finally  with  distilled  water,  until 
no  reaction  is  obtained  for  silver  or  chlorine.  The  now  pure 
gold  is  carefully  drained  and  dried  and  melted  in  a  clay  crucible 
with  bisulphate  of  potash  and  borax,  and  poured  into  a  stone 
mould.  On  removal  of  slag  on  cooling,  and  treating  with  hot 
distilled  water,  pure  cast  gold  is  obtained. 

Chemical  Tests  for  Gold. — Many  auriferous  minerals, 
such  as  iron,  copper,  and  arsenical  pyrites  and  tellurides, 
contain  gold  in  such  a  finely  divided  condition  disseminated 
throughout  the  mass,  that  it  cannot  be  detected  by  the  eye  or 
by  "panning."  Chemists  and  assayers,  however,  are  armed 
with  very  delicate  tests  for  gold  in  minerals  of  this  kind,  so  that 
when  the  precious  metal  has  been  rendered  soluble,  a  quantity 
so  minute  as  one  part  of  gold  in  100,000  parts  of  solution  can 
be  detected  with  certainty. 

The  two  principal  reagents  used  in  testing  for  gold  are 
protosulphate  of  iron,  or  green  vitriol  (FeSO4)  and  bichloride 
*  Vide  Fourth  Annual  Report  of  the  Mint  (1873). 


CHEMICAL   PROPERTIES   OF   GOLD.  IQ 

of  tin,  or  stannous  chloride  (SnCL2).  If  the  substance  under 
examination  be  a  mineral,  it  is  first  ground  to  fine  powder  in 
an  iron  mortar ;  if  an  alloy,  filings  or  turnings  are  obtained.  In 
either  case,  the  substance  is  heated  with  nitro-hydrochloric 
acid  until  all  that  is  soluble  is  dissolved.  After  evaporating 
off  excess  of  acid,  the  mass  is  diluted  with  water,  and  any 
insoluble  matter,  such  as  quartz,  etc.,  filtered  off.  If  any  gold 
is  present,  it  is  now  in  solution  as  gold  chloride  (AuCl3).  The 
liquid  is  then  divided  into  two  portions.  To  one  portion  is 
added  a  solution  of  protosulphate  of  iron  in  excess.  If  gold 
is  present,  an  immediate  precipitate  of  the  metal  is  obtained  as 
a  dark-brown  powder ;  but  if  present  in  minute  quantities,  only 
a  brownish  coloration  is  produced  which,  after  standing  for 
some  time,  is  precipitated,  the  reaction  being  2AuCl3  + 
6FeSO4  -  2Au  +  2Fe,(SO4)3  +  Fe.2Cl6. 

To  the  second  portion  a  dilute  solution  of  tin  bichloride 
(SnCU),  containing  a  small  quantity  of  tin  tetrachloride,  or 
stannic  chloride  (SnCl4),  is  added.  If  gold  is  present,  a  beauti- 
ful purple  precipitate  is  produced,  purple  of  Cassius ;  if  present 
only  in  minute  quantities,  a  purple  solution  is  the  result.  Any 
brown  precipitate  obtained  by  FeSO4  in  the  first  portion  of  the 
original  solution  can  be  filtered  off,  dissolved  in  aqua  regia, 
and  the  gold  present  confirmed  by  adding  the  chloride  of  tin 
to  the  liquid,  when  the  purple  precipitate  or  solution  will  be 
obtained. 

Another  delicate  test  for  gold,  which  will  detect  the  metal 
if  present  only  to  the  extent  of  a  few  grains  to  the  ton  of 
mineral,  consists  in  treating  100  grams  of  the  finely  divided 
and  roasted  ore  with  100  c.c.  of  an  alcoholic  solution  of  iodine, 
and  allowing  it  to  stand  for  an  hour,  with  occasional  stirring. 
On  allowing  it  to  settle,  a  piece  of  Swedish  filter  paper  is 
soaked  with  the  clear  solution.  This  is  then  dried  and  ignited. 
If  gold  is  present,  the  remaining  ash  will  be  coloured  purple, 
and  this  can  be  confirmed  by  treating  the  ash  with  bromine 
water,  and,  on  adding  some  tin  chloride  solution,  the  purple 
of  Cassius  is  obtained. 


SAMPLING   OP   GOLD    ORE. 

CONSEQUENT  upon  the  very  uneven  and  sparse  distribution 
of  gold  in  the  "  veins "  and  "  placers,"  the  obtaining  of  an 
average  sample  is  attended  with  some  difficulty ;  but  in  ascer- 
taining the  intrinsic  value  of  auriferous  ores,  it  is  very  necessary 
that  great  care  should  be  exercised  in  obtaining  an  average 
sample,  and  none  but  experienced  and  competent  persons 
should  be  entrusted  in  obtaining  it,  many  thousands  of  pounds 
having  been  wasted  by  capitalists  through  fraudulent  and 
incompetent  sampling,  it  being  so  easy  to  pick  out  lumps  of 
ore  from  a  mass  that  will  contain  an  amount  of  gold  far 
exceeding  that  which  would  be  obtained  in  actual  extraction 
on  a  commercial  scale. 

The  assay er  may  be  called  upon  to  ascertain  the  amount  of 
gold  contained  in  a  "lode"  or  "reef"  at  various  depths  from 
the  surface,  and  he  must  use  his  judgment  as  to  the  certainty 
of  obtaining  a  sample  that  will  give  an  average  of  the  amount 
of  gold  contained  in  the  ore  at  the  various  depths. 

Of  a  given  weight  of  crushed  ore,  it  is  generally  assumed 
that  5  per  cent.  (2^-)  of  the  mass  taken  at  regular  intervals, 
and  of  equal  weight,  will  give  an  average  representation  of  the 
amount  of  gold  contained  in  the  whole  bulk.  The  amount  of 
work  attending  the  accurate  sampling  of  a  mass  of  ore  will 
depend  upon  its  amount,  hardness,  and  whether  it  is  in  lumps 
or  in  powder,  since  it  is  necessary  that  the  actual  average 
sample  taken  for  assay  should  be  finely  divided. 

Suppose  we  have  a  parcel  of  lump-gold  ore,  which  we  will 
call  A.  Out  of  every  twentieth  scoop-,  spade-,  bag-,  barrow-,  or 
truck-load  of  ore,  according  to  the  amount  thereof,  we  extract 


UNIVERSITY 

OF 


. 
SAMPLING   OF   GOLD   ORE.  2I 

one  such  load,  and  make  a  second  heap  of  ore  —  call  this  B  — 
which  will  now  contain  one-twentieth  of  the  bulk  of  A.  We 
now  crush  B  until  it  contains  twenty  times  as  many  stones  or 
particles  as  A,  then  mix  and  abstract  one-twentieth  as  before, 
making  a  third  heap,  C.  This  is  again  reduced  in  fineness 
by  grinding  as  before,  and  the  process  continued  until  a  degree 
of  fineness,  by  sieving,  is  obtained  that  will  fit  the  sample  for 


FIG.  i.— BRAUN  ORE-SAMPLE  CRUSHER  AND  PULVERIZER. 

assaying.     The  general  reduction  of  the  original  parcel  to  the 
small  average  sample  may  be  illustrated  thus  : — 

A  =  1000        tons  of  rock  and  lumpy  ore. 
B  =      50  ,,     rough  stones,  one-twentieth  of  A. 

C  =        2'5  ,,     small  stones,  one-twentieth  of  B. 

D=        cri25        ,,     coarse  powder,  one-twentieth  of  C. 
etc.,  etc. 

Crushing  and  grinding  the  Sample. — There  are 
various  forms  of  pulverizing  implements  for  obtaining  an 
average  sample  for  testing  and  assaying.  At  gold-mines,  where 
thousands  of  tons  of  ore  are  crushed  monthly,  the  stamp  battery 
and  heavy  ball  and  roll  mills  are  in  vogue ;  but  we  shall  de- 
scribe here  only  those  appliances  generally  in  use  by  assayers. 

The  following  is  a  description  of  the   Braun   ore-sample 


22 


GOLD   ASSAYING. 


crusher,  which  reduces  the  lump  ore  to  rough  powder,  and 
which  may  be  operated  by  either  hand  or  power : — 

The  important  and  novel  feature  of  this  machine  is  a  com- 
bination of  a  jaw  and  a  roll  pulverizer  working  together.  The 
part  called  the  stationary  jaw  in  other  types  of  rock-crushers 
is  in  the  Braun  crusher  and  pulverizer  composed  of  an  upper 
stationary  jaw,  A  (Fig.  2),  against  which  the  heavy  breaking 
takes  place,  and  a  lower  part,  B,  which  is  a  roll  revolving 
toward  the  discharge  outlet  only  (backward  rotation  being 
prevented  by  means  of  roller  stops  or  chokes,  C). 

The  lower  portion  of  the  vibratory  jaw  D  is  shaped  to 


FIG.  2.— BRAUN  ORE-SAMPLE  CRUSHER,  IN  SECTION. 

describe,  when  in  operation,  a  segment  of  a  circle  from  the 
axial  point  E,  as  indicated  by  the  dotted  lines  in  Fig.  2.  Thus 
the  discharge  outlet  is  always  the  same  size,  and  permits  the 
operator  to  regulate  the  maximum  size  of  the  crushed  product. 
The  size  of  the  discharge  outlet  can  be  changed  in  a  moment 
by  means  of  a  simple  screw  adjustment. 

A  glance  at  the  illustration  (Fig.  2)  will  show  that  a  down- 
ward motion  is  imparted  to  the  material  being  crushed  by  the 
forward  or  closing  movement  of  the  vibratory  jaw,  D,  and  that 
this  motion  is  compelled  and  continued  by  the  one-way  motion 
of  the  roll,  which  is  towards  the  discharge  outlet. 


SAMPLING   OF  GOLD   ORE.  23 

When  the  vibratory  jaw  recedes  or  opens,  the  upward 
motion  of  the  lower  portion  of  it  raises  the  material  being 
crushed,  thus  presenting  new  surfaces  to  be  crushed  each  time 
the  jaws  come  together. 

The  entire  jaw  A  may  be  removed  by  loosening  a  wedge 
with  one  blow  of  a  hammer.  This  simple  operation  exposes 
the  crushing  surfaces  of  the  machine  in  shape  to  be  easily 
cleaned.  Provision  is  also  made  for  readily  removing  the  roll 
portion  B ;  this  gives  access  to  the  entire  interior  and  all  parts 


FIG.  3. — GEOLOGIST'S  HAMMERS. 

of  the  machine.  The  possibility  of  "salting"  subsequent 
samples  is  entirely  obviated. 

The  crushing  plates  are  tempered  cast  steel  and  are  re- 
versible, and,  when  both  ends  are  worn  out,  may  be  replaced  at 
a  small  expense.  The  pulverizing  roller  has  a  chilled  surface. 
This  machine  is  very  light  running,  all  bearings  being  brass. 

The  weight  of  the  machine  is  225  Ibs.  net,  and  when  crated 
for  shipment,  285  Ibs.  The  jaws  are  3^  inches  wide,  and  the 
roll  6  inches  in  diameter. 

Large  lumps  are  broken  by  geologists'  hammers  (Fig.  3) 
to  the  desired  size  for  further  reduction  by  the  machine. 

Mortars. — For  the   reduction  of  coarse  grains  of  small 


24  GOLD   ASSAYING. 

quantities  of  ore  to  powder  of  requisite  fineness,  usually  of  a 
degree  that  will  pass  through  a  sieve  containing  sixty  to  eighty 
meshes  to  the  lineal  inch,  iron  mortars  and  pestles,  of  the  forms 
shown  in  Fig.  4,  are  much  used;  and  for  grinding  very 
small  quantities  of  ore  to  an  impalpable  powder,  the  agate 
mortar  and  pestle  shown  in  Fig.  5  is  used. 


FIG.  4.— IRON  MORTARS  AND  PESTLES. 


A  new  form  of  mortar,  which  is  not  so  laborious  to  use  as 
the  foregoing,  is  Calkins'  gyratory  mortar  (Fig.  6). 

This  gyratory  mortar  is  designed  to  pulverize  small  ore 
samples  to  any  desired  degree  of  fineness,  such  samples 
having  previously  been  crushed  in  a  rock-breaker  or  ore- 
crusher. 

It  consists  of  an  iron  mortar  having  an  opening  or  dis- 
charge outlet  in  the  bottom,  and  a  round  iron  ball  or  pestle, 


SAMPLING   OF   GOLD   ORE. 


the  contour  of  which  conforms  exactly  to  the  entire  bottom  of 
the  mortar.  About  one-sixth  (£)  of  the  area  of  the  ball  comes 
in  actual  contact  with  the  bottom  of  the  mortar  when  no 
substance  intervenes;  this  construction  gives  the  maximum 
amount  of  grinding  surface. 


FIG.  5.  —  AGATE 
MORTAR  AND 
PESTLE. 


FIG.  6. — CALKINS'  GYRATORY  MORTAR. 

The  machine  is  operated  by  turning  a  handle,  which  is 
supported  by  a  bale  or  arch  over  the  mortar.  A  right-angled 
clutch  extension  attached  to  the  shaft  of  the  handle  imparts 
a  gyratory  and  rotary  motion  to  the  ball.  The  right-angled 
extension  of  the  rotary  shaft  clutches  a  box  fitted  to  the  shaft 
in  the  ball,  which  forces  a  gyratory  motion,  yet  allows  the 
metal  being  crushed  to  produce,  by  attrition,  a  revolution  of  the 
ball  in  an  opposite  direction  to  the  way  it  is  being  gyrated. 
This  peculiar  motion  effects  a  twisting,  crushing  and  grinding, 


26 


GOLD  ASSAYING. 


and  prevents  the  material  being  pulverized  from  being  thrown 
ahead  of  the  ball  by  centrifugal  force.  This  is  the  most 
important  feature  of  the  appliance.  A  disruptive  movement 
is  obtained,  and  the  material  forced  to  discharge  through  the 
opening  in  the  bottom. 


FIG.  7.— CALKINS'  GYRATORY  MORTAR,  IN  SECTION  AND  DETAIL. 

Tight  engagement  between  the  ball  and  the  mortar  is 
obtained  by  a  coil  spring  around  the  shaft,  which  at  its  lower 
end  presses  against  the  ball,  and  at  its  upper  end  against  the 
box  on  the  shaft  of  the  ball. 

The  pestle  being  a  true  sphere,  and  the  lower  portion  of  the 
mortar  which  comes  in  contact  with  it  being  an  arc  of  a  true 
circle,  the  parts  wear  to  place,  and  never  become  ineffective 
by  use. 

The  bale  or  arch  is  hinged  at  one  side  and  secured  by  a 
thumb-screw  at  the  opposite  side,  which  permits  the  entire 
inside  to  be  easily  accessible  for  cleaning  by  swinging  the  bale 


SAMPLING  OF   GOLD   ORE.  27 

over  as  shown  in  Fig.  7,  which  allows  the  ball  to  be  readily 
lifted  out. 

Bucking-plate  and  Hammer. — A  desirable  form  of 
pulverizer  in  use  is  the  bucking-plate  and  hammer  shown  in 
Fig.  8.  It  consists  of  a  smooth  iron  plate  about  2  feet  square, 
surrounded-  with  a  rim  about  i  inch  high  around  three  sides, 
and  a  hammer  having  a  smooth  curved  surface  weighing  about 
8  Ibs.,  and  a  handle  30  inches  long. 


FIG.  8. — BUCKING-PLATE  AND  HAMMER. 

The  ore,  in  coarse  grains,  is  spread  over  the  surface  of  the 
plate,  and  the  hammer  manipulated  upon  it  with  both  hands, 
one  holding  the  handle  and  the  other  pressing  the  head  down- 
wards, and  rubbed  with  an  oscillatory  movement  of  the  handle 
until  the  ore  is  reduced  to  the  desired  state  of  fineness.  An 
improved  form  of  the  implement  is  Calkins'  radial  bucking- 
plate,  shown  in  the  woodcuts  (Figs.  9  and  10). 

Calkins'  Combined  Radial  Bucking-plate  and 
Hammer. — This  machine  will  quickly  reduce  crushed  ore 
samples  to  a  pulp  of  any  desired  fineness  with  the  expenditure 
of  but  a  fraction  of  the  energy  and  time  required  for  the  same 
work  on  the  old-style  bucking-plate. 


28 


GOLD   ASSAYING. 


It  consists  of  a  circular  plate,  to  the  sides  of  which  is 
journaled  an  axle  carrying  the  shoe  or  muller.  The  tight 
engagement  between  shoe  and  plate  is  effected  by  two  spiral 


Fie;.  9. — CALKINS'  COMBINED  RADIAL  BUCKING-PLATE  AND  HAMMEK. 

springs,  which  admit  of  a  much  lighter  shoe  than  would  other- 
wise be  required,  and  at  the  same  time  gives  a  more  lively 
action  to  the  shoe. 


Vertical  Section  5hoiuioa 
'///jj  material  ciulbroolicalkj  re|eedioq 


FIG.  jo.— CALKINS'  COMBINED  RADIAL  BUCKING-PLATE  AND  HAMMER,  IN  SECTION. 

Heavier  or  lighter  engagement  between  shoe  and  plate  may 
be  had  by  compressing  or  relaxing  the  spiral  springs.  The 
shoe  is  actuated  by  means  of  a  handle  connected  to  its  shaft. 


SAMPLING  OF   GOLD   ORE.  29 

The  grinding  surfaces  of  the  shoe  and  plate  conform  in  shape 
exactly  to  each  other. 

Both  ends  of  the  plate  depart  somewhat  tangentially  from 
the  true  radial  line  of  the  grinding  surface;  this  prevents  the 
sample  from  being  thrown  out  of  the  plate  accidentally  while 
in  operation.  One  end  of  the  plate  does  not  so  radically  depart 
from  the  radial  line  as  the  other,  and  at  this  point  it  is  provided 
with  a  metal  screen  of  any  desired  mesh,  so  that,  in  operating, 
such  of  the  material  being  crushed  as  may  be  fine  enough  will 
be  thrown  against  and  will  fall  through  into  a  receptacle. 

From  time  to  time  the  muller  may  be  swung  clear  of  the 
plate,  and  the  material  in  the  plate  may  be  brushed  against  the 
screen,  thus  liberating  the  product  that  is  ground  to  the  requisite 
fineness. 

Both  ends  of  the  shoe  terminate  in  a  sharp  edge,  which  as 
it  works  gathers  up  the  coarse  particles  of  the  ore,  and  as  the 
shoe  approaches  the  extremity  of  the  plate,  these  particles  roll 
or  slide  over  the  top  surface  of  the  muller  and  enter  a  cross-wise 
aperture  on  the  centre  of  the  shoe,  and  are  thus  automatically 
replaced  between  the  grinding  surface  of  the  plate  and  muller, 
as  shown  in  sectional  drawing  in  Fig.  10. 

The  importance  of  this  construction  of  the  shoe  will  be 
readily  apparent,  as  by  gathering  up  the  coarser  particles  it 
prevents  them  from  being  surrounded  and  protected  by  the 
finer  particles,  which  would  be  the  case  were  not  the  coarser 
particles  scraped  up  and  replaced  between  the  grinding  surface 
of  shoe  and  muller  at  each  stroke. 

The  screen  is  held  in  place  by  a  thumb-screw,  which 
permits  of  ready  removal,  in  case  it  is  necessary  to  clean  or  to 
insert  screen. 

This  plate  never  becomes  ineffective  through  wear,  as  the 
grinding  surfaces  wear  to  each  other. 

Length 18  inches 

Width 6      „ 

Net  weight          .         ._ 75  Ibs. 

Weight,  packed  for  shipment      ....  100    „ 

Quartering. — An  important  operation  in  the  reduction  of 


30  GOLD  ASSAYING. 

the  amount  of  powdered  ore  is  quartering.  The  whole  of  the 
mixed  ore  is  heaped  up  into  a  cone,  and  then  by  means  of  a 
wooden  stirrer  is  stirred  circuitously,  gradually  from  the  centre 
until  it  becomes  flattened  out  into  a  low  frustum  of  a  cone. 
Two  diameters  at  right  angles  to  each  other  are  now  lined  out 
on  the  surface  with  a  straight-edge,  any  two  alternate  quarters 
are  mixed  together  and  reserved,  and  the  others  rejected. 
This  process,  with  or  without  further  grinding,  as  may  be 
required,  may  be  repeated  with  the  reserved  portion  until  the 
requisite  quantity  is  obtained  for  assay. 

An  ingenious  apparatus  on  the  cone  principle  is  the  labora- 
tory divider  of  Mr.  Clarkson,  illustrated  in  Fig.  n,  which  will 


FIG.  ii. — CLARKSON'S  LABORATORY  DIVIDER. 

divide  up  a  sample  into  six  equal  and  exactly  similar  portions 
in  less  than  the  same  number  of  seconds,  ensuring  agreements 
in  the  assay  from  any  of  the  portions. 

Preparing  the  Powdered  Sample  for  Assay. — It  is 

essential  that  the  whole  of  the  average  sample  obtained  by 
whatever  mode  of  pulverizing  is  adopted  should  pass  through 
a  60-  to  8o-mesh  sieve.  Should  there  be  any  particles  of 
metallic  gold  that  could  not  pass  through,  owing  to  their 
malleability,  these  must  be  cupelled  separately,  and  their  value 


SAMPLING   OF  GOLD   ORE.  31 

calculated  per  ton  of  ore  on  the  quantity  they  were  sifted  from, 
independently  of  the  result  obtained  by  the  true  assay,  to 
which  amount  it  may  be  afterwards  added.  The  sieves  usually 
used  are  the  tin-box  sieves,  which  contain  several  of  various 
degrees  of  mesh  (Fig.  12),  and  the  ordinary  wooden-frame 
sieve,  with  brass  gauze  of  specific  mesh  (Fig.  13). 

The  prepared  sample  should  be  stored  in  labelled  tin  boxes 
or  glass  bottles ;  bags  are  somewhat  objectionable,  owing  to  fine 
particles  of  gold  finding  their  way  into  the  fibre  from  the  ore. 

Prior  to  the  subjection  of  the  ore  to  the  various  assay 
operations,  a  definite  weight  should  be  decided  upon  to  be 


FIGS.  12,  13. — SIEVES. 

taken,  depending  upon  the  approximate  amount  of  gold  and 
silver  found  by  preliminary  assay. 

The  amount  of  gold  found  present  in  auriferous  ores  is 
expressed  in  this  country  and  in  Australia  in  terms  of  ounces, 
pennyweights,  and  grains  per  English  "long  ton"  of  2240  Ibs. 
=  32,666  troy  ounces;  while  in  America  and  South  Africa  the 
amount  is  expressed  in  terms  of  ounces,  pennyweights,  and 
grains  per  "short  ton"  of  2000  Ibs.  =  29,166  ozs.  troy. 
Much  inconvenience  would  be  prevented  if  the  French  metric 
system  of  weights  and  measures  were  universally  used.  It  will 
be  used  for  weighing  operations  throughout  this  little  work, 
while  tables  will  be  given  for  conversion  into  the  English  and 
American  terms  of  expression. 

Before  weighing  out  the  sample  (pulp)  for  assay,  the  whole 
of  it  should  be  spread  out  on  a  sheet  of  glazed  paper  by  means 
of  a  steel  spatula  (Fig.  14),  and  by  its  means  small  quantities 


32  GOLD  ASSAYING. 

are  taken  up  from  all  over  the  mass,  and  conveyed  to  the  left- 
hand  pan  of  the  pulp  balance  until  the  requisite  weight — 
generally  either  25,  50,  or  100  grams — is  obtained.  There  are 


FlG.    14. — Sl'ATULA. 


various  types  of  balances  used  for  this  purpose,  Figs.  15,  16, 
and  17,  being  convenient  forms.  They  are  sensitive  to  about 
i  centigram  with  a  load  of  500  grams.  The  weights  (Fig.  18) 


FIGS.  15,  16,  17.— PULP  BALANCES. 

from  500  grams  to  o'oi  gram  are  contained  in  a  wooden  box, 
being  manipulated  therefrom  by  means  of  a  forceps  (Fig.  19). 

The  amount  decided  upon  having  been  weighed  out,  the 
next  operations  consist  of — 


SAMPLING   OF   GOLD 


OFTH^ 

UNiVERS 

CF         33 

"^^*L  I FO^ti^"**  ^ 

(1)  Fusion. — A  process  in  which  the  wholeot  triegold 
and  silver  is  dissolved  by  molten  lead  produced  by  reduction 
of  its   oxide  by  reducing  and  fluxing   agents  in  a  fire-clay 
crucible  at  a  bright-red  heat. 

(2)  Scorification. — Not  an  absolutely  necessary  operation, 
but  a  convenience,  and  consists  in  the  reducing  of  the  bulk  of 
the  lead  produced  by  fusion  by  converting  the  bulk  of  it  into 
oxide  or  slag,  and  thus  concentrating  the  silver  and  gold  in  a 
small  lead  button  for  subsequent  cupellation.    Scorification  can 
also  be  applied  to  sulphide  ores  in  assaying  for  gold  without 
previous  roasting. 

(3)  Cupellation. — This  is  a  process  in  which  the  lead 
button  contained  in  a  receptacle  of  bone  ash  is  subjected  to 


FIG.  18.— WEIGHTS. 


FIG.  19. — FORCEPS. 


heat  in  a  current  of  air  in  a  muffle,  whereby  the  lead  is  con- 
verted into  oxide  and  absorbed  by  the  cupel,  leaving  a  "  pril " 
or  "  button  "  of  silver  and  gold  behind. 

(4)  Parting. — This  process  consists  of  dissolving  out  the 
silver  by  nitric  acid,  leaving  the  gold  in  a  pure  state  for 
weighing. 


FUSION. 

IN  order  to  effect  the  solution  of  gold  in  the  ore  with  lead, 
the  ore  is  mixed  with  fluxes,  the  amount  and  nature  of  which 
depend  upon  the  nature  and  amount  of  ore  taken.  The 
operation  is  carried  out  in  a  fire-clay  crucible  (Fig.  20).  The 
crucibles  made  by  the  Morgan  Crucible  Company  are  the  best 
for  the  purpose ;  they  should  be  of  such  size  that  when  the  ore 
and  fluxes  are  introduced  they  should  not  be  more  than  two- 
thirds  full.  The  materials  necessary  for  mixing  with  the 


FIG.  20. — FIRE-CLAY  CRUCIBLE.  FIG.  21. — FIRE-CLAY  ROASTING  DISH. 

powdered  ore  under  assay  are  powdered  borax,  carbonate  of 
soda,  oxide  of  lead  free  from  silver,  flour  or  carbon,  and  occa- 
sionally nitre.  Should  the  ore  under  examination  be  refractory 
— that  is,  contain  such  elements  as  sulphur,  arsenic,  antimony, 
tellurium,  etc. — the  weighed  sample  should  be  first  carefully 
roasted  with  occasional  stirring  in  a  roasting  dish  (Fig.  21), 
this  operation  being  conducted  in  a  muffle  furnace  (Fig.  36). 
Care  should  be  taken  to  heat  the  ore  gradually,  and  not 
heat  it  suddenly  to  a  high  temperature,  otherwise  there  will  be 
a  loss  of  gold.  With  "  free  milling  "  or  quartz  ore  free  from 
iron  pyrites  or  mundic,  previous  roasting  will  be  unnecessary. 


FUSION. 


35 


The  weighed  quantity  of  the  ore — a  most  convenient 
quantity  to  take  being  50  grams,  or  100  grams  when  very  low 
grade — is  mixed  on  a  sheet  of  glazed  paper  by  means  of  a 
spatula.  The  following  are  the  charges  for  different  types  of 
ore : — 


Ore. 

Flour 
Litharge 
Soda  carbonate 
Borax 
Silica 


Quartz.        5°  per  cent,  quartz.     AU  oxides        Calcareous 

Vu*"1^-  cr>  ivr  rpnt-_  mrirfoc  urines.  rt«.c 


Grins. 
50 

5 

40 
60 
15 


50  per  cent,  oxides. 

Grins. 

5° 

5 

40 

50 
25 


Grins. 
50 

5 
40 

25 
50 


Grms. 
50 

5 

40 
10 
5° 
25 


The  crucible  having  been  previously  gradually  heated  to  a 
dull  red  heat — sudden  heating  may  cause  the  crucible  to  crack — 


FIGS.  22,  23,  24. — CRUCIBLE  TONGS. 


the  well-mixed  charge  is  run  into  it,  and  carefully  conveyed,  by 
means  of  crucible  tongs  (Figs.  22,  23,  and  24  are  convenient 
types),  to  the  assay  furnace  already  heated  to  redness. 

The  Assay  Furnace. — There  are  various  forms.  At  large 
mines  a  permanent  brickwork  furnace,  which  also  contains  one 
or  more  muffles,  is  used  and  heated  by  means  of  coke  or  char- 
coal. The  most  convenient  form  of  furnace  for  single  assays, 
where  gas  is  available,  is  Fletcher's  gas  assay  furnace 


36  GOLD   ASSAYING. 

(Fig.  25),  consisting  of  an  iron  burner  arranged  to  admit  air 


FIG.  25.— ASSAY  FURNACE  (GAS). 


FIG.  26.— ASSAY  FURNACE  (CHARCOAL). 

with  the  gas  before  ignition,  as  in  the  Bunsen  burner;   the 


FUSION.  37 

heating  chamber  is  of  fire-brick,  and  an  iron  chimney  creates 
the  draught,  and  carries  away  the  products  of  combustion. 

A  form  of  furnace  much  used  in  gold-mines  is  Morgan's 
charcoal  furnace  (Fig.  26).  This  consists  of  fire-brick  bound 
together  with  hoop-iron.  Its  construction  will  be  readily  seen 
from  the  sketch.  The  draught  is  produced  by  a  chimney  20  to 
30  feet  high.  A  small  charcoal  fire  is  first  kindled,  the  hot 


FIG.  27.— ASSAY  FURNACE  (OIL). 


crucible  and  its  charge  placed  in  it,  and  covered  around  and 
over  with  small  lumps  of  charcoal;  the  cover  having  been  placed 
on,  a  white  heat  is  soon  obtained. 

Where  gas,  charcoal,  or  coke  is  not  available,  Nelson's 
portable  oil  furnace  is  useful  (Fig.  27). 

In  this  furnace  a  mixture  of  oil  vapour  and  air  is  the  source 
of  heat.  The  light  petroleum  is  contained  in  a  strong  steel 
cylinder,  supplied  with  an  air-pump,  pressure  gauge,  etc.  The 
compressed  air  forces  the  oil  from  the  cylinder  in  a  fine  stream  ; 
it  is  mixed  with  air,  and  burnt  in  a  specially  constructed  burner, 


38  GOLD   ASSAYING. 

the  flame  from  which  enters   the   aperture   of  the  fire-brick 
furnace,  as  seen  in  the  sketch. 

The  crucible  and  its  contents  are  kept  in  the  furnace  at  a 
bright-red  heat  until  complete  fusion  has  occurred  and  effer- 
vescence subsided,  which  generally  takes  place  in  about  half 
an  hour.  The  crucible  is  now  taken  out  of  the  furnace  with 


FIG.  28. — INGOT  MOULD. 

the  tongs,  and  its  contents  carefully  poured  into  an  ingot  mould 
(Fig.  28)  as  quickly  as  possible.  The  slag  is  allowed  to  over- 
flow, the  reduced  lead  containing  the  gold  and  silver  collecting 
in  the  bottom  of  the  mould.  When  cold,  the  mould  is  turned 
upside  down,  and  the  button  of  lead  detached  from  the  slag 
by  tapping  with  a  hammer  on  an  anvil.  The  lead  button  is 
now  flattened  out,  and  is  next  subjected  to  the  process  of 
cupellation. 


CUPELLATION. 

THIS  operation  is  carried  out  in  small  cup-shaped  receptacles 
made  of  compressed  bone  ash.  Fig.  29  shows  elevation  and 
section  of  one ;  it  will  be  observed  that  they  have  a  slight 
taper.  The  cupels  produced  in  the  Royal  Mint  are  made  in 
special  steel  cupel  moulds. 

There  are  two  types  in  use,  illustrated  by  Figs.  30  and  31. 
Fig.  30  shows  a  mould  for  making  single  cupels,  and  Fig.  31 
a  mould  that  produces  four  cupels  at  one  time.  They  consist 
of  a  plunger  C,  a  guide  B,  and  the  mould  A.  Bone  ash  which 
has  been  slightly  damped  with  a  dilute  solution  of  carbonate 
of  potash,  is  placed  in  the  mould  A,  just  a  little  more  than 
will  completely  fill  it;  the  guide  B  is  then  placed  over  it; 
the  plunger  C  introduced,  which  is  then  subjected  to  pressure 
under  a  lever  press.  On  dismantling,  the  bone  ash  will  have 
assumed  the  form  shown  in  Fig.  29.  Before  use,  the  cupels 
should  be  very  carefully  dried  and  stored  in  a  dry  place, 
otherwise  they  are  very  liable  to  crack  and  form  fissures 
during  cupellation,  which  would  render  the  assay  worthless. 

A  recent  American  invention  is  Calkins'  automatic  cupel 
machine,  illustrated  in  Fig.  32,  for  which  it  is  claimed  that  it 
will  turn  out  six  hundred  cupels  of  perfect  shape,  uniform  in 
size  and  density,  in  one  hour.  The  machine,  as  seen  in  sketch, 
consists  of  a  compound  lever  of  ingenious  construction,  a 
plunger  or  die,  and  two  discs.  The  top  disc  contains  the 
holes  in  which  the  cupel  is  compressed,  and  the  bottom  disc 
is  a  plane  plate  with  one  hole  somewhat  larger  than  in  the 
disc  above.  A  hopper  is  attached  to  the  machine,  in  which 
the  bone  ash  properly  moistened  is  placed.  A  strong  wheel 


GOLD   ASSAYING. 


in  the  hopper  bears  on  the  top  disc,  and  rotates  as  the  machine 
is  worked,  thus  preventing  the  moist  bone  ash  from  bridging 
in  the  hopper,  and  ensures  a  perfect  automatic  and  uniform 
feed.  The  machine  is  manufactured  by  F.  W.  Braun  and  Co., 
of  Los  Angeles,  California. 

Now,  the  object  of  cupellation  is  to  separate  the  lead  which 


FIG.  29. — CUPEL. 


FIG  30.— CUPEL  MOULD 
(MINT). 


FIG.  31. — QUADRUPLE  MOULD 
USED  AT  ROYAL  MINT. 


has  been  used  to  dissolve  gold  and  silver,  in  the  case  of  gold 
ores,  and  in  the  case  of  bullion,  to  separate  the  added  lead 
and  the  oxidizable  metals  originally  present  in  the  bullion. 
Bone  ash,  at  a  bright-red  heat,  owing  to  its  porosity,  has  the 
property  of  absorbing  oxide  of  lead  and  other  oxides,  such  as 
those  of  copper,  bismuth,  zinc,  etc.,  which  are  soluble  in  oxide 
of  lead ;  while  metals  which  do  not  oxidize  in  the  atmosphere, 


CUPELLATION.  41 

such  as  gold,  silver,  platinum,  etc.,  are  not  absorbed.  This 
property,  then,  is  the  principle  upon  which  cupellation  is  based. 
The  cupel  must  be  large  enough  to  absorb  the  whole  of  the 
oxidizable  metals  associated  with  the  precious  metals,  and  the 
absorptive  power  of  the  cupel  depends  upon  its  texture,  porosity, 
etc.  A  cupel  of  average  porosity  will  absorb  the  fused  oxide 
produced  from  about  its  own  weight  of  lead.  In  the  assay  of 
bullion,  the  amount  of  lead  necessary  to  add  will  depend  upon 
the  amount  of  oxidizable  metal  present ;  the  more  the  latter, 
the  more  lead  is  required. 

The  following  table  shows  the  proportion  of  lead  necessary 
for  the  elimination  of  varying  amounts  of  copper  in  bullion  :— 

Lead  required  for 

Gold  in  alloy.  i  part  alloy. 

1000  thousandths I  part 


900 
800 
700 
600 
500 


10  parts 

16 

22 

24 

26 


400,  300,  200,  ico,  50  thousandths  .         .         .         •    .  34 

The  actual  operation  of  cupellation  is  carried  on  in  a  fire- 
clay muffle  (Fig.  33)  heated  by  coke,  charcoal,  oil,  or  gas  in 


r 


FIG.  32.— CALKINS'  AUTOMATIC  CUPEL  MACHINE.        FIG.  33.— FIRE-CLAY  MUFFLE. 

furnaces  to  suit  various  conditions.  The  muffle  has  slits 
in  the  sides  and  back  to  admit  air,  which  is  essential  to 
cupellation. 

There  are  numerous  forms  of  furnace  in  use.    The  form 
used  in  the  Royal  Mint  is  illustrated  by  Figs.  34  and  35,  showing 


42  GOLD   ASSAYING. 

front  elevation  and  vertical  section.  The  muffle  M  rests  on 
a  bed  of  fire-clay,  supported  on  an  iron  girder  plate,  C,  resting 
upon  the  fire-bars  B.  The  external  portion  of  the  furnace  is 
made  of  wrought-iron  about  f  inch  thick,  the  whole  being  lined 
with  fire-bricks. 

There  are  five  openings  to  the  furnace.     The  bottom  one, 


FIGS.  34,  35.— MUFFLE  FURNACE  (MINT). 

A,  is  a  convenience  for  clearing  the  ash-pit ;  the  two  side  ones, 
DD,  to  remove  two  fire-bars  so  as  to  admit  of  the  fuel  being 
dropped  into  the  ash-pit  when  necessary;  F  is  an  opening 
through  which  fuel — a  mixture  of  coke  and  coal  is  most  suit- 
able— is  charged;  E  is  the  snaffle  opening  into  which  are 
introduced  the  cupels,  crucibles,  or  scorifiers. 


CUPELLATION. 


43 


The  chimney  is  supplied  with  a  damper,  and  with  this,  in 
conjunction  with  the  various  openings,  the  requisite  degree  of 
draught  can  be  regulated  to  suit  the  various  degrees  of  heat 
that  may  be  required. 

A  convenient  form  of  furnace  for  prospecting  and  laboratory 
work  is  seen  by  the  illustration  (Fig.  36),  and  can  be  used  for 


FIG.  36. — PROSPECTOR'S  MUFFLE  FURNACE. 


muffles  up  to  8  X  4^  X  3  inches,  or  four  Battersea  round 
crucibles  G,  three  ditto  F,  or  two  ditto  G,  and  adapted  for 
fusing,  melting,  and  cupellation,  and  constructed  of  wrought- 
iron  lined  with  fire-clay.  The  sketch  shows  the  furnace  for 
cupellation.  If  required  for  melting  or  fusing,  remove  the 
muffle  C  and  close  aperture  with  the  fire-clay  plug  D.  It  is 
supplied  with  a  sand-bath,  G,  most  useful  for  drying  cupels, 


44 


GOLD   ASSAYING. 


evaporations,  etc.      Coke,  charcoal,  or  coal   is   used  as  fuel, 
or  mixtures  of  them. 

Another  useful  form  of  portable  muffle  furnace  is  seen 
illustrated  in  Fig.  37  for  use  with  coke  and  charcoal.  It  is 
made  in  sections  of  fire-clay  bound  with  iron  bands.  The 
working  of  the  furnace  will  be  readily  understood  from  the 
sketch,  a  is  the  socket  on  which  a  long  iron  chimney  is  fitted ; 
b,  the  opening,  provided  with  a  plug,  for  charging  the  fuel ; 


FIG.  37. — MORGAN'S  MUFFLE  FURNACE  (CHARCOAL'). 


c,  the  muffle ;  d,  the  door  for  muffle ;  <?,  muffle  arch ;  /,  door 
for  stirring  fire ;  gt  the  door  for  regulating  draught :  h,  support 
for  muffle ;  and  z,  iron  grating.  The  chimney  is  provided  with 
a  damper  to  regulate  draught  for  desired  temperature. 

A  most  convenient  and  useful  form  of  muffle  furnace  is 
shown  in  section  sketch  (Fig.  38),  for  use  where  gas  is  avail- 
able. All  the  inconveniences  of  coke  and  charcoal  furnaces 
due  to  attention  to  stirring,  to  ash,  clinkers,  dust,  etc.,  are  here 
avoided,  and  an  even  temperature  can  be  maintained  for  any 


CUPELLATION. 


45 


length  of  time  by  regulating  gas  and  air  supply,  without  further 
trouble.  The  furnace  is  constructed  of  fire-clay  bound  with 
iron  bands,  and  adapted  for  various-sized  muffles.  It  rests  on 
a  large  draught  Bunsen  burner,  and  is  provided  with  an  iron 
chimney. 

Another  form  of  muffle  furnace  is  Nelson's,  in  which  ben- 
zoline  oil  is  used  as  fuel.  Its  construction  will  be  understood 
from  the  illustration  seen  in  Fig.  39. 

It  consists  of  the  muffle  furnace  A,  constructed  of  sheet- 
iron  lined  with  fire-clay ;  an  oil  reservoir,  B,  provided  with  air- 


FIG.  38.— FLETCHER'S  MUFFLE  FURNACE  (GAS). 

pump,  valves,  and  gauge,  connected  with  the  vaporizer;  and 
burner,  D,  at  which  the  mixture  of  oil-vapour  and  air  burns, 
and  the  flame,  entering  the  back  of  the  furnace,  surrounds  the 
muffle.  This  furnace  will  be  found  useful  in  localities  where 
coal,  coke,  or  charcoal  is  unavailable. 

A  compact  and  portable  necessary  apparatus  for  prospectors, 
etc.,  is  illustrated  in  Fig.  40,  and  is  neatly  packed  for  transport 


46 


GOLD  ASSAYING. 


purposes.    It  is  supplied  by  Messrs.  Fletcher,  Russell,  and  Co., 
Limited,  of  Warrington,  and  comprises — 

No.  4  muffle  furnace,     \ 

No.  3  crucible  furnace,  >  modified  for  oil. 

Four  spare  muffles,         ) 

Two  spare  crucibles. 

One  spare  burner  coil. 

Bow  and  plain  tongs. 

Oil  storage  tank. 

Size  of  case,  29  X  27  X  19  ins. 

Weight,  packed,  146  Ibs. 


CUPELLATION. 


47 


Having  now  described   cupels  and   cupellation,   and   the 
furnaces  necessary  for  carrying  out  the  process,  we  will  proceed 


to  describe  the  methods  of  extraction  of  gold  from  the  lead 
button  obtained  as  described  on  p.  38. 


48  GOLD   ASSAYING. 

Cupellation  of  the  Lead  Button. — The  muffle  furnace 
having  been  charged  with  fuel,  and  the  fire  started,  the  cupels 
are  introduced  into  the  muffle  by  means  of  cupel  tongs  (Fig. 
41),  the  bottom  of  the  muffle  being  previously  covered  with 
a  thin  layer  of  bone  ash.  The  muffle  having  been  raised  to 
an  orange-red  heat,  the  lead  button  is  conveyed  to  the  cupel 
with  the  tongs.  Should  the  muffle  be  already  raised  to  the 
desired  temperature  prior  to  the  introduction  of  the  cupels, 
then  the  latter  should  be  gradually  pushed  into  the  muffle  from 
its  mouth,  since  sudden  heating  would  be  liable  to  cause  cracks. 
The  button  immediately  melts,  and  assumes  a  convex  form, 
resembling  a  globule  of  oil.  The  lead  is  rapidly  oxidized 
superficially ;  the  molten  oxide,  in  which  is  dissolved  any  other 


FIG.  41.— CUPEL  TONGS. 

oxidizable  metals,  is  rapidly  absorbed  by  the  cupel — some, 
however,  escaping  from  the  muffle  in  the  form  of  fumes — and 
the  button  gradually  diminishes  in  size,  until  but  a  small  bead 
or  bullion  containing  the  gold  remains.  When  it  is  seen  that 
the  button  no  longer  diminishes  in  size,  the  cupel  is  gradually 
drawn  to  the  mouth  of  the  muffle.  It  must  not  be  suddenly 
taken  out  to  the  cool  air,  otherwise  there  may  be  loss  from 
spurting  due  to  sudden  liberation  of  gases,  mainly  atmo- 
spheric oxygen. 

Immediately  before  the  button  sets  it  emits  a  flash  of  light 
called  fulgnration  or  coruscation^  and  bright  iridescent  bands 
play  on  its  surface ;  this  phenomenon,  indicating  the  termina- 
tion of  the  process,  will  always  be  remembered  when  once 
observed.  After  the  cupel  has  been  taken  out  of  the  muffle 
and  allowed  to  cool,  the  button,  which  should  have  a  clean 
convex  surface,  is  detached  by  means  of  the  end  of  a  penknife, 
brushed,  and  conveyed  to  the  left-hand  pan  of  the  assay 
balance  with  a  forceps,  for  weighing. 


CUPELLATION. 


49 


Weighing  the  Button. — This  important  operation  is 
performed  by  means  of  the  assay  balance.  There  are  numerous 
types  of  this  delicate  instrument  in  use.  A  description  of  the 
one  illustrated  in  Fig.  42  will  suffice  to  explain  the  principle 
upon  which  they  are  constructed  and  manipulated.  The 
weights  are  made  of  platinum  and  aluminium,  the  set  con- 
taining from  i  gram  (=  1000  milligrams)  to  i  milligram,  with 


FIG.  42.— OERTLING'S  ASSAY  BALANCE.    (Beam  6  inches  long.} 


milligram  riders  for  manipulation  on  graduated  scales  on  the 
arms  of  the  beam  AA.  The  balance  can  thus  be  made  to 
indicate  y^  milligram  in  weight.  The  weights  are  contained 
in  compartments  in  a  small  box  (Fig.  43),  so  as  to  keep  them 
from  getting  astray  and  from  dust.  They  are  conveyed  to  and 
from  the  balance  by  means  of  the  forceps  (Fig.  19,  p.  33). 

The  mechanism  of  the  balance  is  fixed  in  a  glass  case  with 
sliding  door,  so  as  to  keep  away  dust  and  also  air-currents 
during  weighing.  The  graduated  beam  AA,  which  is  6  inches 


5O  GOLD   ASSAYING. 

long,  is  made  of  brass,  and  when  oscillating  the  central  steel 
knife-edge  is  supported  on  an  agate  plane.  The  stirrups  C,  C, 
made  of  German  silver,  are  suspended  from  the  ends  of  the 
arms  by  means  of  hooks.  The  pans  D,  D,  resting  on  the  stirrups, 
are  made  of  silver ;  the  pan  supports  E,  E  have  a  screw  adjust- 
ment ;  the  agate  support  for  the  beam  at  H  is  manipulated 
by  the  milled  head  F,  which  is  connected  with  an  eccentric 
at  foot  of  pillar  B.  When  at  rest,  the  central  steel  knife-edge 


FIG.  43. — ASSAY  WEIGHTS. 

of  the  beam  is  raised  just  clear  of  the  agate  plane  at  H  by  the 
supports  at  top  of  the  pillar.  On  turning  F  to  the  left,  a  rod 
running  through  B  and  carrying  the  agate  plane  is  raised, 
bringing  the  agate  plane  into  contact  with  the  steel  knife-edge, 
thus  setting  the  balance  in  action. 

It  will  be  observed  that  there  are  pointers  protruding  from 
the  ends  of  the  beam ;  these  oscillate  immediately  in  front  of 
the  divisions  engraved  on  the  ivory  plates  #,  x,  and  indicate 
when  the  balance  is  in  equilibrium,  and  also  the  correct 


CUPELLATION.  5 1 

weight  obtained.  The  final  adjustment  of  the  necessary 
weight  is  obtained  by  manipulating  a  "rider" — these  are  seen 
in  the  centre  of  the  weight-box  (Fig.  43) — suspended  at  y, 
by  means  of  the  sliding-rods  J,  J,  to  the  correct  part  of  the 
graduated  beam  AA,  each  division  of  which  represents  y^ 
milligram. 

It  is  necessary  that  the  balance  should  be  perfectly  level, 
and  for  this  purpose  it  is  provided  with  spirit-levels,  G,  G,  the 
levelling  being  adjusted  by  the  levelling-screws  T,  T.  In  order 
to  keep  the  atmosphere  inside  the  balance  dry,  to  minimize 


FIG.  44.— PORTABLE  ASSAY  BALANCE  FOR  PROSPECTORS. 


rusting,  hygroscopic  substances — such  as  calcium  chloride, 
recently  burnt  quicklime,  or  anhydrous  sulphuric  acid — should 
be  kept  inside  in  a  shallow  dish  or  beaker. 

The  button  having  been  deposited  in  the  left-hand  pan, 
weights  should  be  placed  in  the  right-hand  pan  until  short  of 
about  5  milligrams.  The  case  is  then  closed,  and  the  rider 
moved  on  the  beam  until  it  is  placed  on  a  point  that  allows 
the  beam  to  oscillate  the  same  number  of  divisions  above  and 


52  GOLD   ASSAYING. 

below  the  centre  of  the  ivory  scales  x,  x.     The  correct  weight 
of  the  button  is  then  noted. 

A  handy  form  of  portable  assay  balance  for  use  by  pro- 
spectors is  illustrated  in  Fig.  44.  It  is  sensitive  to  yV  milli- 
gram, and  can  be  packed  in  a  light  flat  case,  which  can  be 
strapped  and  carried  by  hand. 


PARTING. 

THE  button  of  gold  obtained  from  ores  by  the  methods  de- 
scribed almost  invariably  contains  some  silver,  and  it  therefore 
becomes  necessary  to  separate  this  from  the  gold  in  order  to 
get  an  accurate  result.  To  separate  silver  from  gold,  advantage 
is  taken  of  the  fact  that  silver  is  soluble  in  nitric  acid,  forming 
nitrate  of  silver,  while  gold  is  insoluble.  It  is  necessary,  how- 
ever, that  the  silver  should  be  present  to  the  extent  of  at  least 
two  and  a  half  times  the  proportion  of  gold  present ;  if  not, 
the  silver  is  only  partly  dissolved,  as  a  consequence  of  the 
excess  gold  cloaking  as  it  were  the  action  of  the  acid  on  the 
silver.  By  having  the  latter  in  excess,  the  solvent  action  of 
the  acid  upon  it  converts  the  metal  into  a  porous  mass,  and 
thus  the  large  surface  exposed  allows  of  the  complete  extraction 
of  the  silver. 

To  the  weighed  button  is  added  two  and  a  half  times  its 
weight  of  chips  of  silver-foil  or  wire,  and  the  whole  is  wrapped 
up  in  a  piece  of  lead-foil  free  from  silver,  weighing  about  ij 
gram,  and  this  is  conveyed  by  tongs  to  a  red-hot  cupel  in  a 
muffle,  and  subjected  to  cupellation  in  the  manner  described 
on  p.  39.  The  resulting  button  of  gold  and  silver  is  now 
placed  on  a  polished  steel  block  or  anvil  (Fig.  45),  and 
flattened  into  a  thin  disc  by  carefully  tapping  with  the  flat 
surface  of  a  metallurgical  hammer  (Fig.  46). 

The  flattened  metal  is  now  conveyed  with  the  forceps  to  a 
porcelain  crucible  (Fig.  47).  10  c.c.  of  nitric  acid  (2  of  strong 
acid  to  i  of  water)  are  poured  upon  it,  and  a  watch-glass  placed 
over  the  top.  The  whole  is  now  transferred  to  a  sand-bath  or 
hot  plate,  and  heated  to  boiling.  It  will  be  seen  that  the  acid 


54 


GOLD  ASSAYING. 


rapidly  attacks  the  silver,  which  in  the  course  of  10  minutes 
will  have  all  gone  into  solution,  leaving  pure  gold  as  a  spongy 
mass  in  the  original  form  of  the  disc  if  the  silver  was  under 
three  parts  to  one  part  of  gold  present ;  but  if  more  than  three 
parts  of  silver  be  present,  then  the  gold  will  have  fallen  to 
powder,  and  settled  on  the  bottom  of  the  crucible  as  such.  The 


FIG.  45. — STEEL  ANVIL. 


FIG.  46.— METALLURGICAL  HAMMER. 


crucible  is  now  filled  with  distilled  water  by  aid  of  a  wash- 
bottle  (Fig.  48),  and  the  contents  stirred  with  a  glass  rod; 
the  gold  rapidly  settles  at  the  bottom.  The  clear  solution  is 
now  decanted  from  the  sediment  very  carefully,  and  the  crucible 
again  filled  with  distilled  water,  stirred  and  decanted  as  before, 
until  the  washings  show  no  turbidity,  when  a  few  drops  of 


FIG.  47.— PORCELAIN  CRUCIBLE. 


FIG.  48.— WASH-BOTTLE. 


hydrochloric  acid  or  solution  of  salt  are  added  to  it,  showing 
that  all  nitrate  of  silver  has  been  washed  out  of  the  gold. 
Generally  four  or  five  washings  are  sufficient. 

The  final  washing  and  draining  having  been  accomplished, 
the  crucible  and  contents  are  very  carefully  dried  in  a  water 
oven,  and  finally  brought  to  a  dull-red  heat  over  a  spirit-lamp. 


PARTING. 


55 


When  cool,  the  gold,  in  the  form  of  powder  or  in  one  spongy 
piece,  is  transferred  by  the  combined  aid  of  the  end  of  a  pen- 
knife and  camel-hair  brush  to  the  left-hand  pan  of  the  assay 
balance,  and  the  weight  observed.  The  difference  between 
this  weight  and  the  original  weight  prior  to  the  elimination  of 
silver  will  represent  the  quantity  of  silver  present  in  the  sample 
taken. 

The  following  table  facilitates  the  calculation  of  the  result 
per  "long"  and  "short"  ton  and  the  French  ton  of  1000 
kilogs. : — 

ASSAY  TABLE. 
50  grams  taken. 


Alilligramsot  v.  ,, 

gold  or  silver        Yield  per  ton  of  2000  Ibs.    Yield  per  ton  of  2240  Ibs.      Velc  P?F  tor 
obtained.  OI  I00°  KUOSS- 


10 


I 

5 
4 
3 

2 
I 

0-8 
07 
0-6 
0-5 

0-3 

0'2 
O'l 
0-05 


ozs. 

dwts. 

grs. 

ozs. 

dwts. 

grs. 

5 

16 

16 

6 

10 

16 

5 

5 

0 

5 

17 

14 

4 

13 

8 

5 

4 

13 

4 

i 

16 

4 

ii 

12 

3 

10 

0 

3 

18 

10 

2 

18 

8 

3 

5 

8 

2 

6 

16 

2 

12 

6 

1 

15 

o 

1 

19 

5 

I 

8 

I 

6 

3 

O 

ii 

16 

O 

13 

2 

O 

10 

12 

O 

ii 

ig 

0 

9 

8 

o 

IO 

II 

o 

8 

4 

0 

9 

3'5 

0 

7 

0 

o 

7 

20 

o 

5 

20 

0 

6 

13 

0 

4 

16 

o 

5 

5'5 

o 

3 

12 

0 

3 

22 

o 

2 

8 

0 

2 

1475 

0 

I 

4 

0 

I 

7'5 

o 

O 

14 

0 

0 

16 

grins. 
200 

180 
160 
140 

120 

100 

80 
60 
40 

20 

18 
16 
14 

12 

10 

8 
6 
4 

2 
I 


SCORIFICATION. 

Assay  of  Concentrates,  Sulphides,  Arsenides,  and 
Tellurides,  by  Scorification. — This  method  is  in  vogue  for 
the  assay  of  rich  refractory  ores  without  previous  roasting,  the 
principle  of  which  is  to  convert  the  silica  and  other  constituents 
of  the  ore  into  scoria  or  slag,  brought  about  by  oxidation  of 
metallic  lead  by  the  atmosphere,  instead  of  using  oxide  of  lead 
as  in  the  ordinary  assay.  The  excess  of  lead  used  contains  all 
the  gold  and  silver  contained  in  the  ore,  while  any  sulphur, 
tellurium,  arsenic,  are  oxidized  partly  by  the  oxide  of  lead 
produced,  and  partly  by  direct  oxidation  in  the  atmosphere. 


FIG.  49.— SCORIFIER.  FIG.  50.— SCORIFYING  TONGS. 

The  process  is  carried  on  at  a  bright-red  heat  in  a  muffle 
in  a  scorifer  (Fig.  49).  This  is  a  cup-shaped  receptacle  made 
of  compact  refractory  fire-clay  to  withstand  the  corrosive  action 
of  the  molten  lead  oxide ;  it  is  manipulated  to  and  from  the 
muffle  by  means  of  the  scorifying  tongs  (Fig.  50). 

The  process  is  carried  out  as  follows :  4  grams  of  the  powdered 
ore  are  first  intimately  mixed  with  three  to  five  times  its  weight 
of  granulated  lead  free  from  silver,  and  about  half  a  gram  of 
borax.  This  mixture  is  run  into  the  scorifier,  and  covered  over 
with  about  12  grams  of  granulated  lead,  and  introduced  into 
the  muffle  at  a  bright-red  heat.  The  door  of  the  muffle  is 
closed  for  about  a  quarter  of  an  hour  so  as  to  melt  the  charge, 
and  then  opened  so  as  to  let  in  a  current  of  air  through  the 


SCORIFICATION.  57 

muffle.  The  lead  is  now  rapidly  oxidized,  and  attacks  the 
oxidizable  metals  present — most  of  the  arsenic,  sulphur,  and 
tellurium  escaping  as  oxide  fumes — and  converts  them  into  a 
fluid  slag.  It  is  desirable  to  occasionally  introduce  about 
i  gram  of  powdered  charcoal  on  to  the  charge,  by  which  means 
a  portion  of  the  lead  oxide  is  reduced  to  the  metallic  state, 
which,  in  passing  as  small  globules  through  the  mass  of  molten 
scoria,  carries  with  it  to  the  bottom  of  the  scorifier  any  traces 
of  gold  or  silver  that  may  still  exist  in  it.  The  process  is 
known  to  have  terminated  when  a  small  iron  rod,  previously 
heated  to  redness,  is  introduced  into  the  fluid  mass,  and  on 
its  withdrawal  the  adhering  film  of  scoria  runs  off  clean. 

The  scorifier  is  now  taken  out  of  the  muffle,  and  its  contents 
rapidly  poured  into  an  ingot  mould  (Fig.  28).  The  button 
containing  the  gold  and  silver  settles  in  the  metallic  state  in 
the  bottom  of  the  mould,  by  reason  of  its  greater  gravity,  and 
the  litharge  and  other  metallic  oxides  settle  as  a  brittle  mass 
on  the  top.  When  cold,  the  adhering  slag  is  separated  from 
the  lead  button  by  tapping  with  a  hammer,  and  the  latter  is 
then  cupelled  as  described  on  p.  39,  parted,  and  weighed.  If 
the  ore  be  low  grade,  several  weighed  portions  of  the  ore  can 
be  subjected  to  the  process,  and  the  several  lead  buttons 
obtained,  melted  together,  further  scorified,  and  finally 
cupelled. 

Assays  of  pyritic  ores  and  concentrates  can  also  be  made, 
without  previous  roasting,  in  an  ordinary  crucible  by  using 
excess  of  litharge  and  also  nitre ;  but  it  is  necessary  to  know 
by  preliminary  assay  what  proportion  of  sulphides,  etc.,  are 
present,  in  order  to  ascertain  the  necessary  proportion  of 
fluxes,  etc. 

The  following  table  shows  the  charges  for  ores  containing 
10,  50,  and  80-90  per  cent,  sulphides  • — 


GOLD  ASSAYING. 


10  per  cent, 
sulphides. 

50  per  cent, 
sulphides. 

80-90  per 
cent, 
sulphides. 

Ore. 

Glass        . 

grms. 

25 
12 

grms. 

25 
12 

grms. 
25 

Flour 

Litharge 

Soda 

Borax 

Nitre 

Salt 

Iron 


60 
40 


60 
40 


4'5 


100 
34 
30 

40 

35 


Should  there  be  any  iron  matt  formed,  more  nitre  should 
be  added  in  a  repeat  assay.  If  too  large  a  button  of  lead  is 
produced,  this  should  be  reduced  by  scorification.  The  salt  is 
added  as  a  covering. 


ASSAY   OP   BULLION. 

Expressing  the  Gold  Value. — The  intrinsic  value  of 
bullion  being  directly  proportional  to  the  amount  of  pure  gold 
it  contains,  its  accurate  assay  for  the  noble  metal  becomes  a 
matter  of  great  importance.  Unrefined  bullion,  as  received  at 
the  Mint  from  the  reduction  works  and  cyanide  plants,  in- 
variably contains  silver,  and  often  more  or  less  quantities  of 
copper,  lead,  antimony,  zinc,  tin,  and  iron.  Silver  is  present 
as  a  consequence  of  its  being  present  in  the  original  ore ;  the 
copper  may  be  present  owing  to  a  little  finding  its  way  into  the 
gold  amalgam  scraped  from  the  amalgamated  copper  plates  of 
the  gold-mills,  and  also  from  the  accidental  introduction  of  old 
cartridge-cases,  etc.,  with  the  ore  into  the  stamp  battery.  The 
introduction  of  metallic  oddments  into  mills  with  the  ore,  such 
as  pieces  of  tin  plate,  solder,  galvanized  iron,  nails,  etc.,  is 
occasionally  the  cause  of  a  base  bar. 

There  are  two  systems  in  use  for  expressing  the  value  of 
bullion. 

(i)  The  amount  of  gold  present  is  expressed  in  terms 
of  "  carats,"  absolutely  pure  gold  being  expressed  as  being 
24  carats;  each  carat  is  divided  into  four  imaginary  grains, 
and  these  again  are  subdivided  into  eighths  and  "  excess 
grains,"  one  carat  grain  representing  60  excess  grains ;  so  that 
the  unit  weight  or  "  assay  pound "  being  taken,  its  divisions 
may  be  understood  from  the  following  table  : — 


6o 


GOLD   ASSAYING. 


Excess  grains. 

Decimal  equiva- 
lent. 

Eighths. 

Carat  grains 

b 

240 
5760 

Per  cent. 
0-017 
OT30 
1*042 
4-167 
lOO'OOO 

Carats. 

Assay 
pound. 

I 

8 
768 

I 
96 

I 

24 

I 

It  will  be  seen  that  the  excess  grain  is  the  7TV-jr  part  of  the 
metal  taken  for  assay,  the  ratio  being  the  same  as  that  of  the 
grain  to  i  Ib.  troy. 

The  English  standard  gold  coinage  is  22  carats,  that  is,  in 
every  twenty-four  parts  of  the  coin  there  are  twenty-two  parts 
of  gold  and  two  parts  of  copper,  or  it  contains  91*667  per  cent, 
of  pure  gold.  The  "  trade  system  "  of  reporting  the  value  of 
alloy  does  not  generally  give  the  amount  of  gold  present,  but 
states  the  results  as  being  so  much  better  or  worse  than  the 
standard,  indicated  by  prefixing  the  letter  B  or  W,  as  the  assay 
demands.  Thus,  if  an  assay  be  returned  as  B  i  ct.  3  grs. 
5  eighths  +  3*5  excess  grains,  it  means  that  this  amount  added 
to  22  carats  gives  the  actual  amount  in  carats  or  twenty-four 
parts  of  alloy. 

(2)  The  decimal  system  as  used  in  France  and  America,  is 
far  more  simple  and  sensible  than  the  carat  system.  In  it  the 
amount  of  gold  present  is  expressed  in  thousandths,  or  parts  of 
gold  in  1000  parts  of  bullion.  Thus  in  France  and  America 
the  standard  gold  coin  is  expressed  as  being  900  thousandths 
fine,  that  is,  in  every  1000  parts  there  are  900  parts  of  gold  and 
100  parts  of  copper,  or  90  per  cent,  of  gold  and  10  per  cent, 
of  copper.  The  English  standard,  22  carats,  is  represented  in 
the  decimal  system  as  being  916-667  thousandths  fine. 

From  the  following  table  results  can  be  calculated  from  one 
system  into  the  other  : — 


ASSAY   OF   BULLION. 


6l 


Carat.        '<  Decimal  equivalent. 

Carat  grains.  Decimal  equivalent. 

j 

4I-667 

I 

10-417 

2 

83-333                          2                          20-833 

3 

125-000                  3                 31*250 

4 

166-667                   4                  41*667 

208-131 

250-000 
291*667 

Eighths.       Decimal  equivalent. 

333-333 

9 

10 

375-000 
416-667 

I 
2 

1-302 
2-604 

ii                 458-222 

12                       500-000 

3                   3-906 

4                           T208 

I3                       5U-667 

5 

6-510 

14                       583*333 

6 

7-812 

15                       625-000 

7 

/    ***• 

1  6                 666-667 
17                 708-333 

8 

10-417 

18                750-000 
19                791-667 

20                      833-333 

Excess 
grains. 

Decimal  equivalent. 

21                       875-000 

22                       916*667 

I 

2 

0-174 
0-347 

24                    lOOO'OOO 

3 
4 

0-52I 
0-694 

5 

0-868 

6 

1*072 

7 

1-215 

7'5 

1-302 

Process  of  Assay. — The  method  described  will  be  that 
in  vogue  at  the  Royal  Mint,  and  consists  of — 

(1)  The  accurate  weighing  and  preparation  of  the  assay 
•piece  or  sample.     In  the  case  of  ingots,  two  corners,  one  from 
the  top  and  one  from  the  bottom,  are  chipped  off  with  a  cold 
chisel. 

(2)  Cupellation,  or  removal  of  copper  or  other  oxidizable 
metals  by  oxidation  and  absorption  in  bone  ash. 

(3)  Parting  by  inquartation,  or  separation  of  silver  from 
the  gold  by  nitric  acid. 

(4)  Final   weighing  of  the  gold  "cornet,"  and  applying 
necessary  corrections  as  a  result  of  assaying  the  same  weight 
of  pure  gold  under  the  same  conditions. 


62 


GOLD   ASSAYING. 


Preparation  and  Weighing  of  Assay  Piece. — In  the 
Mint,  when  a  gold  bar  is  to  be  assayed,  two  chips  are  cut  off 
with  a  chisel,  one  from  the  top  corner  and  the  other  from  the 
bottom  corner.  These  are  rolled  out  into  thin  strips  by  means 
of  the  "cornet"  rolls.  Fig.  51  illustrates  the  latest  design  of 


FIG.  51.— CORNET  ROLLS. 

rolls  essential  to  gold  assaying.  The  top  roll  will  be  observed 
at  A,  the  bottom  one  being  immediately  underneath.  They 
are  revolved  by  hand  by  means  of  the  double  pair  of  cogs  B,  B, 
any  desired  pressure  being  obtained  by  manipulating  the 
screw  C.  A  feed-plate  that  is  tangent  to  the  contact  point  of 
both  rolls  obviates  the  difficulty  of  inserting  a  small  piece  of 
bullion  between  the  rolls — a  common  source  of  trouble  in 
ordinary  rolls.  The  button  to  be  rolled  is  placed  on  the  feed- 


UNIVERSITY 

OF 
ASSAY  OF  BULLlI 

plate,  and  may  be  easily  pushed  with  a  pair  of  pincers  between 
the  rolls.  Opposite  the  feed- plate,  where  the  metallic  strip 
emerges,  there  is  another  plate  that  closely  wipes  the  bottom 
roll,  and  conducts  it  away  from  the  rolls.  This  prevents  the 
strip  from  dropping  on  to  the  floor  or  becoming  lost. 

The  two  chips  are  rolled  into  thin  plates,  and  cut  up  into 
very  small  pieces  by  means  of  shears  (Fig.  52),  and  then 
mixed,  i  gram  of  this— if  the  metal  is  very  base  bullion — is 
now  accurately  weighed,  or,  if  nearly  pure  gold,  o'5  gram  is 
weighed  for  assay. 

In  many  assay  offices,  about  i  dwt.  of  drillings  are  bored 
out  of  the  top  and  bottom  of  the  bar  and  mixed,  any  bits  of 
steel  that  may  have  been  rubbed  off  the  drill  being  extracted 
by  means  of  a  magnet. 


FIG.  52. — SHEARS. 

As  it  is  necessary  to  add  silver  to  about  two  and  a  half 
times  the  weight  of  gold  present,  it  is  essential  to  know  about 
how  much  already  exists  in  the  bullion.  An  experienced 
assayer  can  approximately  tell,  by  the  colour,  the  amount 
present — the  lighter  the  colour,  the  more  the  silver.  Copper 
gives  a  more  or  less  coppery  colour  to  the  bar.  Frequent 
handling  and  assaying  of  bullion  of  various  values  soon  gives 
one  a  rough  idea  of  its  approximate  value,  by  observation  of 
colour,  hardness,  etc. 

To  ascertain  approximately  the  amount  of  silver,  and  also  of 
the  oxidizable  metals  present,  such  as  copper,  lead,  etc.,  weigh 
i  gram  of  the  clippings  or  drillings  of  the  bullion,  and  wrap  up 
in  30  grams  of  lead-foil,  and  cupel  and  weigh  the  button  of 
gold  and  silver ;  the  difference  in  weight  from  the  gram  taken 
will  equal  the  amount  of  copper,  etc.,  present.  Now  wrap  this 
button,  together  with  3  grams  of  silver,  in  30  grams  of  sheet 
lead  and  cupel.  The  button  thus  obtained  is  hammered  into  a 


64  GOLD   ASSAYING. 

disc,  and  the  silver  dissolved  out  by  nitric  acid  in  a  porcelain 
crucible.  As  there  is  in  this  case  an  excess  of  silver,  the  gold 
will  be  left  in  the  form  of  a  brown  powder.  This  is  washed 
and  filtered,  and  estimated  as  described  on  p.  5  5 .  The  difference 
in  the  weight  of  gold  thus  obtained,  plus  the  weight  of  copper, 
etc.,  found,  from  the  original  gram  taken,  gives  the  amount  of 
silver  present. 

Now,  having  made  an  approximate  determination  of  the 
gold,  silver,  and  base  metals  present,  the  accurate  assay  can  be 
proceeded  with.  0*5  gram,  or  i  gram,  as  the  case  demands, 
of  the  prepared  sample  is  accurately  weighed  on  the  assay 
balance,  and  mixed  with  silver  to  two  and  a  half  times  the 


(JU 


0 

FIG.  53. — GOLD  BUTTONS  AND  CORNETS. 

weight  of  gold  contained  in  it,  as  found  by  preliminary  assay. 
The  two  metals  are  then  wrapped  up  in  30  grams  of  lead-foil, 
and  subjected  to  cupellation  as  described  on  p.  39.  (It  may 
here  be  remarked  that,  to  ensure  accuracy,  a  duplicate  assay 
should  be  simultaneously  made.)  The  button  of  gold  and 
silver  thus  obtained  is  next  prepared  for  treatment  with  nitric 
acid  in  order  to  dissolve  out  the  silver ;  and  for  this  purpose 
the  button  is  rolled  into  a  thin  strip,  and  curled  up  into  a 
shape  known  as  a  "cornet."  Fig.  53  illustrates  the  transition 
from  the  button  to  the  cornet. 

a  is  the  original  button ;  it  is  hammered  into  shape  £,  as 
described  on  p.  53  ;  it  is  then  rolled  into  shape  c  by  means 
of  the  cornet  rolls  (Fig.  51),  and  this  is  coiled  into  the  cornet 
d,  which  still  retains  its  shape  as  pure  gold  after  the  silver  has 
been  eliminated,  but  diminished  in  size  as  seen  in  e. 


ASSAY   OF   BULLION.  65 

The  cornet  d  is  now  introduced  into  a  parting  flask,  C 
(the  illustration  (Fig.  54)  shows  half  a  dozen  of  them  in  one 
stand,  in  which  six  partings  can  be  simultaneously  carried  on), 
and  about  80  c.c.  of  nitric  acid  of  specific  gravity  1*26  poured 
into  it.  It  will  be  observed  that  long  glass  tubes  D  are  inserted 
into  the  necks  of  the  flasks,  which  rest  on  "  rose "  Bunsen 


FIG.  54.— ASSAY  FLASKS. 

burners,  from  which  the  necessary  heat  required  to  effect  the 
solution  of  the  silver  is  obtained  by  means  of  coal-gas.  The 
tubes  condense  most  of  the  acid  vapours  evolved  during  the 
solution  of  the  silver,  while  the  gaseous  oxides  of  nitrogen 
escape.  Here  it  is  necessary  to  remark  that  the  irritating 
fumes  of  the  oxides  of  nitrogen  should  be  conveyed  beyond 
the  pale  of  the  operator. 

The  cornet  and  acid  being  introduced  into  the  flask,  heat 

F 


66  GOLD   ASSAYING. 

is  carefully  applied  until  the  acid  boils,  and  it  is  kept  boiling 
from  3  to  5  minutes,  after  which  the  liquid  is  drained  off 
and  the  cornet  washed  with  distilled  water.  The  cornet  is 
now  boiled  for  15  or  20  minutes  with  about  50  c.c.  of 
nitric  acid  of  specific  gravity  1*30.  To  prevent  "  bumpfhg," 
consequent  from  the  necessity  of  the  freedom  of  vapour  at  the 
bottom  of  the  flask,  a  few  pieces  of  broken  porcelain  about  the 
size  of  peas  are  introduced.  This  prevents  violent  and  sudden 
ebullition.  The  acid  is  now  poured  off,  and  washed  three  or 
four  times  with  20  c.c.  of  distilled  water,  to  free  the  cornets 
from  nitrate  of  silver.  After  the  last  washing  has  taken  place, 
judged  as  described  on  p.  54,  a  porcelain  crucible  is  placed 
upside  down  on  the  tube,  and,  both  held  tight,  it  is  then  in- 
verted; trie  liquid  flows  away,  and  the  cornet  and  pieces  of 
porcelain  are  retained  in  the  crucible.  The  latter  are  taken  out 
by  means  of  forceps,  and  the  cornet  of  the  now  pure  gold  is 
dried  in  the  crucible,  first  in  a  water-bath,  and  then  heated 
over  a  spirit-lamp  (vide  p.  54)  and  weighed,  the  calculation 
of  the  weight  into  carats  or  thousandths  being  determined  by 
reference  to  the  table  on  p.  61. 

Now,  while  the  weight  of  the  pure  gold  in  bullion  thus 
ascertained  will  be  sufficiently  accurate  for  ordinary  purposes, 
in  cases  where  thousands  of  ounces  of  bullion  are  to  be  accurately 
assayed,  the  determination  of  the  absolute  amount  of  gold  present 
will  be  obvious.  There  are  certain  errors  that  may  take  place, 
which  may  be  plus  or  minus  the  result  obtained,  depending 
upon  a  variety  of  circumstances,  including  amounts  of  oxidizable 
metals  present,  temperature  of  cupellation,  etc. ;  and  although 
this  amount  may  not  vary  more  than  0*2  to  0*5  in  1000, 
this  can  be  accurately  determined  by  subjecting  two  or  three 
check  assays  upon  pure  gold — prepared  in  the  manner  described 
on  p.  17 — precisely  under  the  circumstances  as  the  sample  as 
regards  the  amount  taken  for  assays,  amount  of  silver  and  lead 
used,  temperature,  etc.  The  amount  found  may  be  plus  or 
minus  the  amount  originally  taken,  and  this  must  be  added  or  sub- 
tracted from  the  result  of  the  assays  of  the  samples  and  those 
duplicately  conducted  at  the  same  time  and  in  a  similar  manner. 


ASSAY  OF   BULLION.  6/ 

The  correction  to  be  applied  to  a  gold  assay  will  be  evident 
from  the  following  formula  : — 

Let  1000  be  the  weight  of  alloy  taken  ; 

/  =  the  weight  of  the  piece  of  gold  finally  obtained ; 
x  =  the  actual  amount  of  gold  in  the  alloy  expressed  in 

thousandths ; 

a  =>  the  weight  of  gold  (supposed  to  be  absolutely  pure) 

taken  as  a  check,  which  approximately  equals  x ; 

b  =  the  loss  or  gain  in  weight  experienced  by  a  during  the 

process  of  assay,  expressed  in  thousandths ; 
k  =  the  variation  of  "  check  gold  "  from  absolute  purity, 

expressed  in  thousandths ; 
Then  the  actual  amount  of  fine  gold  in  the  check  piece 

/            k    \ 
=  a(i  —  ),  and  x,  the  corrected  weight  of  the  assay  will 

ak 

+  b  •  b  being  added  or  subtracted  according  as  it 


1000 

is  loss  or  gain. 

If  a  be  assumed  to  be  equal  to  xt  the  equation  becomes 

P±b 


1000 

Example — 

Let  /  =  901  "I  thousandths 
a  —  920-0  ,, 

/;  =      0-3          ,,  (gain  in  weight) 

k  —      o-i  ,, 

Then,  by  the  first  formula — 

_  _  920  +  Q'l  _ 

For,  as  b  is  a  gain  in  weight,  it  must  be  deducted  ;  hence— 

x  =  901-1  —  0-092  —  0-3 
=  900-708 

and  by  the  second  formula — 

_  901  i  —  03 
cri 

*~  1000 

=  900  708 


68  GOLD   ASSAYING. 

Determination  of  Gold  by  Wet  Assay. — Advantage 
is  taken  of  the  solubility  of  gold  in  aqua  regia  (2  parts  of 
hydrochloric  acid  to  i  part  nitric  acid)  as  perchloride  (AuCl3), 
and  its  subsequent  precipitation  therefrom  by  reducing  agents 
in  the  pure  metallic  state,  as  a  basis  of  estimating  gold  in  the  wet 
way. 

The  method  adopted  is  as  follows  :  i  gram  of  the  bullion  in 
turnings  or  drillings,  or,  if  a  rich  ore  in  fine  powder,  a  quantity 
that  would  contain  about  0*5  gram  gold,  is  weighed  and  intro- 
duced into  a  100  c.c.  beaker;  about  20  c.c.  of  strong  hydro- 
chloric acid  is  added,  and  the  beaker  covered  over  with  a 
clock-glass,  and  placed  on  a  hot-plate  or  sand-bath.  Strong  nitric 
acid  is  now  gradually  added — about  12  c.c.  will  be  found  suffi- 
cient— and  the  whole  kept  near  the  boiling  point  until  all  that  is 
soluble  is  dissolved.  The  cover  is  now  removed  and  the  liquid 
evaporated  to  dryness  with  10  c.c.  of  strong  hydrochloric  acid. 
When  cold,  5  c.c.  of  HC1  are  added  and  warmed,  and  then 
50  c.c.  of  distilled  water,  and  the  whole  heated  until  all  that 
is  soluble  is  dissolved.  If  ore  was  operated  on  there  would 
doubtless  be  an  insoluble  residue  of  siliceous  matter,  while  in 
the  case  of  bullion  containing  only,  say,  lead  and  copper,  there 
would  be  no  residue.  Silver  would  be  rendered  insoluble  as 
chloride. 

Should  there  be  any  residue,  this  is  filtered  off,  and  the  filtrate 
of  chloride  of  gold,  etc.,  received  in  a  porcelain  basin  of  150  c.c. 
capacity;  the  residue  is  washed  with  hot  distilled  water  till 
free  from  soluble  salts,  and  the  solution  diluted  to  100  c.c. 
It  now  becomes  necessary  to  precipitate  the  gold.  To  effect 
this  a  clear  solution  of  ferrous  sulphate  (FeSO4)  is  added  in 
excess,  and  the  whole  stirred  and  allowed  to  stand  in  a  warm 
place  for  a  few  hours  until  the  whole  of  the  gold  present  has 
subsided  as  a  fine  brown  powder.  The  gold  is  now  filtered 
through  a  Swedish  filter  paper,  and  the  solution  tested  to 
ensure  complete  precipitation  of  gold  by  the  addition  of  more 
FeSO4.  The  amorphous  gold,  thoroughly  washed  from  soluble 
salts  with  hot  water,  is 'now  transferred  to  a  weighed  porcelain 
crucible  with  the  filter,  and  dried  at  the  mouth  of  a  hot  muffle, 


ASSAY   OF   BULLION.  69 

after  which  it  is  gradually  inserted  into  the  red-hot  interior 
until  the  paper  has  all  completely  burnt  off.  The  crucible  is 
now  withdrawn,  cooled  in  a  desiccator,  and  weighed •  the 
increase  in  weight  of  the  crucible  equals  the  weight  of  the  gold 
in  the  sample  taken,  which  can  be  expressed  in  percentage, 
thousandths  or  carats. 

Valuation  of  Gold  sent  to  the  Mint. — To  find  the 
value  per  ounce  of  gold  sent  from  a  mine  to  the  Mint,  divide 
the  standard  gold  by  the  weight  before  melting,  and  multiply 
the  result  by  ^3  17^.  ioj^. 

For  instance,  supposing  the  Mint  return  to  show— 

ozs. 

Weight  before  melting       .         .         .         .         .47*41 
Standard  gold    .  38'  19 

the  calculation  would  be  as  follows  : — 

474 1)38 1 9 -0(0 -805  0^05  x  ^3  i-js. 
3792-8  =  0-805  x  ^3  '894 
-805 


26200 

23705  19470 

311520 

2495 

£3-134(670) 

20 

J.  2-680 
12 


—^3  2s.  8t/.,  value  per  ounce 
of  gold  as  produced 
from  the  mine. 


Assay  of  Minute  Quantities  of  Gold  by  the  Micro- 
scope.*— The  aid  of  the  microscope  for  ascertaining  the 
weight  of  very  small  "  prills  "  of  gold  is  now  often  resorted  to, 
especially  when  the  assay  balance  available  is  not  sufficiently 
sensitive.  For  quantities  of  gold  from  0*5  to  0*005  milligram 

*  Vide  Dr.  Tate's  Paper  to  Liverpool  Polytechnic  Society,  November, 


70  GOLD   ASSAYING. 

a  microscope  with  J-inch  objective  and  B  eye-piece  is  suitable. 
The  measurements  are  made  with  the  help  of  a  scale  engraved 
or  photographed  on  a  circular  piece  of  glass,  which  rests  on 
the  diaphragm  of  the  eye-piece.  This  scale  and  the  object 
upon  the  stage  can  be  easily  brought  into  focus  at  the  same 
time.  The  button  of  gold  obtained  by  cupelling  is  loosened 
from  the  cupel  by  gently  touching  it  with  the  moistened  point 
of  a  knife ;  it  generally  adheres  to  the  knife,  and  is  then  trans- 
ferred to  a  glass  slide.  The  slide  is  placed  on  the  stage  of 
the  microscope,  illuminated  from  below,  and  the  bottom  is 
brought  into  focus,  and  so  placed  that  it  apparently  coincides 
with  the  scale.  The  diameters  in  two  or  three  directions 
(avoiding  the  flattened  surface)  are  then  read  off:  the  different 
directions  got  by  rotating  the  eye-piece.  The  mean  diameter 
is  taken. 

The  weight  of  the  button  is  arrived  at  by  comparing  with 
the  mean  diameter  of  a  standard  prill  of  gold  of  known  weight. 
The  weights  are  in  the  proportion  of  the  cubes  of  the  diameters. 
For  example,  suppose  a  prill  has  been  obtained  which  measures 
12*5  divisions  of  the  scale,  and  that  a  standard  prill,  weighing 
o*i  mg.,  measures  in  divisions.  The  weight  will  be  calcu- 
lated as  follows  : — 

ii'i3  :  i2'53 ::  o-i  :  x 
o-i  x  12-15  x  12-5  x  12-5 
"=    -iiVxik-ilTin-'  =°''43mg. 

The  calculations  are  simplified  by  the  use  of  a  table  of 
cubes.  The  standard  prills  used  in  the  comparison  should  not 
differ  much  in  size  from  the  prills  to  be  determined.  They  are 
prepared  by  alloying  known  weights  of  gold  and  lead,  so  as  to 
get  an  alloy  of  known  composition,  say  i  per  cent.  gold.  Por- 
tions of  the  alloy  containing  the  weight  of  gold  required  (say 
o'i  mg.)  are  then  weighed  off  and  cupelled  on  small  smooth 
cupels,  made  with  the  finest  bone  ash.  Care  must  be  taken  to 
remove  the  cupels  as  soon  as  cupellation  has  finished.  Several 
standard  prills  of  the  same  size  should  be  made  at  the  same 
time,  and  their  mean  diameters  calculated.  The  lead  for 


ASSAY   OF   BULLION.  71 

making  the  gold-lead  alloy  is  prepared  from  litharge  purified 
by  reducing  from  it  about  10  per  cent,  of  its  lead  by  fusion 
'with  a  suitable  proportion  of  flour;  the  purified  litharge  is 
powdered,  mixed  with  sufficient  flour,  and  reduced  to  metal. 

In  determining  the  gold  contained  in  small  buttons  of 
silver-gold  alloy  obtained  in  assaying  (and  in  which  the  silver 
is  almost  sure  to  be  in  excess  of  that  required  for  parting), 
transfer  the  button  from  the  cupel  to  a  small,  clean,  porcelain 
crucible;  pour  on  to  it  a  few  drops  of  dilute  nitric  acid  (50  per 
cent,  in  water),  and  heat  carefully  until  action  has  ceased. 

If  the  residual  gold  is  broken  up,  move  the  crucible  in  a 
manner  that  the  particles  may  cohere.  Wash  three  or  four 
times  with  distilled  water,  half  filling  the  crucible  each  time, 
and  decanting  off  against  the  finger.  Dry  the  crucible  in  a 
warm  place,  and  when  dry,  take  the  gold  up  on  a  small  piece 
of  pure  lead.  Half  a  grain  of  lead  is  sufficient,  and  it  is 
best  to  hold  it  on  the  point  of  a  blunt  penknife,  and  press  it 
on  the  gold  in  the  crucible.  The  latter  generally  adheres. 
Transfer  to  a  small,  smooth  cupel,  and  place  in  the  muffle. 
When  the  cupellation  has  finished,  the  button  of  gold  is 
measured  as  already  described. 

Estimation  of  Proportion  of  Gold  in  Quartz  from 
the  Specific  Gravity. — Should  it  be  desired  to  determine 
the  amount  of  gold  present  in  a  rich  piece  of  quartz  (provided 
no  other  mineral  is  present  in  quantity),  this  can  be  calculated 
with  tolerable  accuracy  from  an  estimation  of  the  specific 
gravity  of  the  sample,  consequent  upon  the  great  difference  in 
the  specific  gravity  of  gold  and  silica — 19*2  and  2*6  respectively. 

A  handy  machine  for  this  purpose  is  Walker's  specific 
gravity  balance  (Fig.  55). 

The  specimen  is  attached  to  a  piece  of  horsehair,  and  sus- 
pended on  to  the  graduated  arm  of  the  balance,  and  its  weight 
first  ascertained  in  air;  it  is  then  weighed  in  water  at  15*5°  C., 
as  in  the  sketch.  Its  weight  in  water  will,  of  course,  be  less  than 
its  weight  in  air,  and  by  dividing  the  difference  into  the  latter 
the  specific  gravity  is  obtained." 


72  GOLD   ASSAYING. 

We   will   now   illustrate    how   the   proportion   of  gold   is 
calculated. 


FIG.  55.  —  WALKER'S  SPECIFIC  GRAVITY  BALANCE. 


Example  — 

Let  A  =  weight  in  grams  of  sample  in  air  ; 

B  =  weight  in  grams  of  sample  in  water  ; 

C  =  specific  gravity  of  gold; 

D  =  specific  gravity  of  quartz  ; 

X  =  weight  of  gold  in  sample  j 

Then  A  —  X  =  weight  of  quartz. 

V 

P  =  weight  of  water  displaced  by  the  gold  in  the  sample 
when  weighed  in  water 

—  •=-  —  =  weight  of  water  displaced  by  the  quartz  in  the  sample 

when  weighed  in  water. 
X      A  —  X 
Then  -^  -\  --  ~-     —  A  —  B  =  total  water  displaced  by  sample. 

DCA-DCB-AC 

--~ 


ASSAYS   IN    CYANIDATION,  CHLORINATION, 
AND   AMALGAMATION   PROCESSES. 

Cyanidation— Synopsis  of  Process.— The  principle  of 
this  process,  commercially  perfected  by  Messrs.  MacArthur 
and  Forrest,  is  based  upon  the  fact  that  a  very  dilute  solution 
of  cyanide  of  potassium  (KCN),  containing  so  small  a  quantity 
as  from  o'i  to  0*5  per  cent,  of  the  salt  in  solution,  dissolves 
finely  divided  gold  from  its  association  with  other  minerals, 
and  that  such  a  dilute  solution  has  a  selective  or  preferential 
solvent  action  on  gold  which  a  stronger  solution  would  not 
have,  numerous  other  minerals  being  soluble  in  strong  but 
insoluble  in  weak  solutions,  the  reaction  taking  place  being — 

2Au  +  4KCy  +  O  +  H2O  =  2KAuCy2  +  2KHO 

the  gold  going  into  solution  as  double  cyanide  of  gold  and 
potassium. 

In  the  ordinary  cyanide  process  air  is  essential,  as  will  be 
seen  by  the  presence  of  oxygen  in  the  above  reaction.  Of 
late,  however,  there  have  been  improvements  made  which  do 
not  necessitate  the  presence  of  air,  small  additions  of  chloro- 
or  bromo-cyanogen  answering  the  same  purpose. 

The  gold  is  precipitated  from  its  combinations  with  potas- 
sium and  cyanogen  with  metallic  zinc  according  to  the 
theoretical  reaction — 

2KAuCy2  +  Zn  =  2Au  +  K2ZnCy4 
and  is  afterwards  smelted  by  well-known  methods. 

Tests  necessary  in  Cyanidation. — These  should  include 


74  GOLD   ASSAYING. 

free  sulphuric  acid  and  other  cyanicides,  such  as  sulphates  and 
basic  sulphates  of  iron,  and  calculation  of  the  amount  of  lime 
or  caustic  soda  necessary  to  neutralize  these ;  the  consumption 
of  cyanide  per  ton ;  the  percentage  of  extraction ;  testing  the 
strengths  of  cyanide  solutions. 

Acidity  of  Gold  Ores. — Should  iron  pyrites  be  present 
in  the  ore,  they  gradually  become  oxidized  in  a  damp  atmo- 
sphere, forming  free  sulphuric  acid  and  sulphate  of  iron,  thus — 

FeS2  +  H2O  +  70  =  FeSO4  +  H2SO4 

Other  basic  sulphates  are  also  formed. 

Free  sulphuric  acid  and  the  sulphates  of  iron  decompose 
potassium  cyanide,  and  unless  they  should  have  been  washed 
out  or  neutralized  with  lime  or  caustic  soda  prior  to  leaching 
with  the  cyanide  solution,  serious  consequences  would  accrue 
— there  would  be  an  undue  amount  of  cyanide  used  up,  and 
the  extraction  would  also  be  low. 

Should  the  ore  be  acid,  stirring  it  with  distilled  water, 
applying  a  blue  litmus,  the  latter  would  be  turned  red. 

Should  it  be  found  necessary  to  determine  the  amount  of 
acid  present  and  the  amount  of  caustic  soda  or  lime  necessary 
to  neutralize  it  prior  to  cyanidation,  the  following  is  a  con- 
venient method  to  adopt : — 

200  grams  of  the  ore  are  weighed  and  transferred  to  a 
beaker,  and  200  c.c.  of  water  poured  on  and  well  stirred.  In 
the  mean  time,  10  grams  of  commercial  caustic  soda  are 
dissolved  in  water  and  diluted  in  a  graduated  vessel  (Fig.  57) 
to  i  litre  (=  1000  c.c.)  and  well  mixed.  A  burette  (Fig.  59) 
graduated  in  ~6  c.c.  is  now  filled  with  this  solution,  and  is 
gradually  run  into  the  beaker  containing  the  ore  and  water, 
stirring  until  a  drop  taken  out  with  the  stirrer  just  turns  red 
litmus  paper  blue.  Each  cubic  centimetre  required  corre- 
sponds to  -^Q  lb.  of  the  same  strength  of  caustic  soda  necessary 
to  neutralize  the  acid  and  acid  salts  contained  in  i  ton  of  the 
ore.  If  the  consumption  be  more  than  3  Ibs.  per  ton,  it  will 
then  be  found  more  economic  to  give  the  ore  a  water  wash 


ASSAYS   IN   CYANIDATION,   ETC.,   PROCESSES.        75 

prior  to  running  on  a  weak  alkaline  wash  and  the  cyanide 
solution  on  the  large  scale. 

Extraction  Tests. — First  make  an  accurate  assay  of  a 
portion  of  the  powdered  sample.  Weigh  out  200  grams  of  the 
sample — should  it  be  acid,  it  is  previously  treated  with  water 
and  alkali  in  the  proportion  that  it  is  proposed  to  use  on  the 
large  scale — and  transfer  to  the  funnel  of  the  apparatus  shown 
n  Fig.  56. 


FIG.  56. — CYANIDE  ASSAY  APPARATUS. 

The  sketch  will  be  readily  understood.  The  apparatus 
consists  of  a  funnel  so  arranged  as  to  imitate  the  cyanide  process 
on  a  small  scale.  The  tube  passes  through  a  cork  fitted  into 
a  flask  which  is  connected  with  a  vacuum  apparatus.  As  will 
be  observed,  the  funnel  is  packed  with  asbestos  and  sand, 
which  acts  as  a  filter.  150  c.c.  of  a  0*5  per  cent,  solution  of 
potassium  cyanide  is  poured  on  the  sample  in  the  funnel,  and 
allowed  to  stand  for  a  couple  of  days,  after  which  a  slight 
vacuum  is  produced  by  turning  on  the  water  sufficient  to  allow 
the  solution  to  gently  trickle  into  the  flask.  When  the  solution 
has  all  drained  through,  the  flask  is  emptied  and  the  funnel 
refitted  into  it,  and  the  solution  again  returned  and  allowed  to 
gently  percolate  as  before. 


76  GOLD   ASSAYING. 

The  length  of  time  necessary  for  complete  extraction  will 
depend  upon  the  nature  of  the  sample  and  the  degree  of  fine- 
ness of  the  gold ;  the  more  minute  the  particles  of  gold,  the 
sooner  its  solution  takes  place.  From  one  to  three  days  should 
be  sufficient  with  the  above  amount  of  "  strong  "  solution. 

When  it  is  assured  that  all  the  soluble  gold  is  dissolved, 
the  solution  is  allowed  to  completely  drain  into  the  flask,  and 
the  remaining  solution  still  clinging  to  the  ore  is  washed  out 
with  water.  '  The  leached  ore  is  now  taken  out  and  dried  in 
a  water  oven  or  on  a  hot  plate,  and  100  grams  taken  and  the 
gold  estimated  in  it,  using  double  the  amount  of  fluxes  given 
on  P-  35>  and  the  result  obtained  by  the  assay  table,  p.  55, 
multiplied  by  2,  will  give  its  assay  value,  and,  subtracting  this 
from  the  original  assay,  the  amount  of  extraction  will  thus  be 
obtained. 

Determination  of  Gold  in  Solution. — It  is  sometimes 
advisable  to  estimate  the  gold  that  has  gone  into  the  solution 
direct.  In  order  to  effect  this,  transfer  the  solution  to  a  large 
porcelain  dish,  and  add  to  it  80  grams  of  litharge,  and  carefully 
evaporate  to  dryness.  Now  add  to  it  30  grams  of  borax,  120 
grams  of  carbonate  of  soda,  and  10  grams  of  flour.  Thoroughly 
mix  the  whole  by  means  of  a  flexible  steel  spatula,  and  transfer 
to  an  assay  crucible,  and  proceed  with  the  assay  as  described  on 
p.  72.  As  200  grams  were  taken,  the  result  obtained  by 
reference  to  the  assay  table  on  p.  55  should  be  multiplied  by  4. 

Another  method  of  determining  the  gold  in  solution  is  to 
add  an  excess  of  a  solution  of  nitrate  of  silver.  This  produces 
a  curdy  precipitate  of  cyanide  of  silver  and  a  double  cyanide  of 
gold  and  silver,  which  rapidly  settles.  This  is  filtered  and 
dried,  and  then  mixed  with  litharge  and  the  usual  fluxing 
materials,  and  fused  in  the  usual  manner.  The  button  of  lead 
obtained  is  cupelled,  the  silver  separated  from  the  resulting 
bullion  with  nitric  acid,  and  the  gold  weighed. 

Determination  of  the  Consumption  of  Potassium 
Cyanide. — The  method  adopted  is  a  simple  volumetric  one, 


ASSAYS   IN   CYANIDATION,   ETC.,  PROCESSES.        77 


and  depends  upon  the  fact  that  if  a  solution  of  nitrate  of  silver 
be  gradually  added  to  a  solution  of  potassium  cyanide,  there  is 
produced  a  double  cyanide  of  potassium  and  silver,  according 
to  the  reaction — 

2KCy  +  AgN03  =  AgKCy2  +  KNO3 

Now,  this  double  cyanide  is  a  white  precipitate,  and  is  soluble  in 
excess  of  potassium  cyanide,  so  that  immediately  the  latter  is  all 


^~e=*S  ^      L 

FIG.  57.— GRADUATED       FIG.  58.— CYANIDE  TEST      FIG.  59.— GRADU- 
FLASK.  FLASK.  ATED  BURETTE. 

decomposed  a  permanent  white  precipitate  takes  place.  This 
forms  the  basis  of  the  method,  which  is  carried  out  as  follows : 
13*05  grams  of  silver  nitrate  are  dissolved  in  pure  water  and 
diluted  to  exactly  i  litre  =  1000  c.c.  in  a  graduated  flask  (Fig. 
57)  and  stocked  in  a  dark-blue  bottle.  The  strength  of  this 
solution  is  thus  so  arranged  that  when  10  c.c.  of  the  sample  of 
cyanide  solution  are  taken  for  testing,  each  cubic  centimetre  of 
the  silver  solution  taken  to  form  a  permanent  white  precipitate 
represents  o'i  per  cent,  of  pure  potassium  cyanide  (KCN)  in 
solution.  10  c.c.  of  the  cyanide  solution  obtained  in  the 
extraction  test  are  poured  into  a  small  flask  (Fig.  58).  A 
burette  graduated  in  -^  c.c.  (Fig.  59)  is  now  rilled  with  the 


78  GOLD   ASSAYING. 

nitrate  of  silver  solution,  and  this  is  gradually  run  into  the 
cyanide  drop  by  drop,  gently  shaking,  until  finally  a  drop 
produces  a  permanent  white  turbidity.  The  volume  of  silver 
solution  consumed  is  now  noted.  Suppose  2*2  c.c.  were 
required,  and  the  original  solution  contained  0*5  per  cent. 
KCN,  then  2*2  x  o'i  =  0*22  per  cent,  in  solution  and  0*50  — 
o'22  =  0-28  per  cent.  KCN  consumed. 

Testing    the    Strength    of    Cyanide    Solutions. — 

Since  the  cyanide  solutions  used  in  extraction  of  gold  are 
used  over  and  over  again,  it  becomes  frequently  necessary  to 
ascertain  the  strength  of  them  in  order  to  know  the  amount  of 
additional  cyanide  necessary  to  add  to  make  them  up  to  the 
required  strength.  The  method  adopted  is  the  same  as  that 
used  to  ascertain  the  consumption  of  cyanide,  10  c.c.  of  the 
solution  being  taken,  and  titrated  with  the  standard  nitrate  of 
silver  solution.  Its  strength  is  thus  ascertained,  and  it  is  then 
necessary  to  calculate  how  much  of  a  strong  solution  contained 
in  the  dissolving  tank  is  necessary  to  add  in  order  to  increase 
its  strength  to  the  required  degree.  The  following  formula 
may  be  used  : — 

A  =  desired  strength  of  stock  solution  per  cent. 

B  =  present  strength         „  „  „ 

C  =  the  strength  of  dissolving  tank  solution  per  cent. 

D  =  the  quantity  in  tons,  Ibs.,  gallons,  litres,  etc.,  of  stock. 

^ T-  X  D  =  quantity  of  dissolving  tank  solution  to  be  added 

U  —  A. 

(in  tons,  Ibs.,  gallons,  litres,  etc.). 

Example. — Supposing  the  stock  solution  to  consist  of  100,000  gallons 
of  0*4  per  cent,  strength,  and  it  be  desired  to  bring  this  up  to  0*6  per 
cent,  by  adding  some  10  per  cent,  solution,  then — 

— — — ^  X  100,000  —  2127*65  gallons  of  the  dissolving  tank  solution. 

Tank  Capacities. — To  calculate  the  cubical  contents  of 
a  circular  tank,  multiply  the  square  of  the  radius^  by  3*14,  and 


ASSAYS   IN   CYANIDATION,   ETC.,   PROCESSES.        79 

the  product  by  the  height  of  the  tank.     Supposing  a  tank  was 
20  feet  in  diameter  and  6  feet  high,  then  — 

io2  x  3'  14  X  6  =  1884  cubic  feet 
i  cubic  foot  of  water  weighs  62-3  Ibs.,  therefore  — 


1884  X'  62-3  =  117573,  and  —  -        =  5878  tons  of  water 

If  it  is  desired  to  prepare  a  0*3  per  cent,  stock  solution,  then 

—  ^  =  352-71    Ibs.    of   cyanide   will    have    to    be 
100 

dissolved  in  it. 

After  treatment  it  is  found  that  the  cyanide  percentage  has 

fallen  to  o'i6,  which  equals  II75^QX       -  =  i88'n  Ibs.  left 

in  solution,  and  to  make  it  again  up  to  0-3  per  cent,  another 
164*61  Ibs.  of  cyanide  must  be  added. 

Extraction  Test  for  Slimes.—  Since  slimes  that  have 
been  cyanided  cannot  be  treated  by  the  ordinary  percolation 
method,  owing  to  the  difficulty  in  nitration,  unless  they  are 
filtered  under  pressure,  the  foregoing  methods  are  modified. 
The  writer  has  found  that  the  apparatus  shown  in  Fig.  60  acts 
admirably  for  slimes  cyanidation. 

It  consists  of  a  cylindrical  glass  jar  clamped  on  to  a 
mechanical  device,  whereby  it  is  made  to  revolve  by  means  of 
a  water  motor  or  by  hand.  The  jar  is  charged  standing 
vertically,  the  mouth  is  covered  with  a  sheet  of  indiarubber, 
the  clamps  are  turned  up  vertically,  and  the  jar  tightly  screwed 
down,  after  which  it  may  be  coupled  to  the  motor  horizontally 
as  seen  in  the  sketch.  200  grams  of  the  slimes  are  introduced 
into  the  cylinder,  together  with  200  c.c.  of  0*2  per  cent,  solu- 
tion of  cyanide,  and  made  to  revolve  about  thirty  revolutions 
per  minute  for  about  12  hours,  after  which  the  cylinder  is 
turned  up  vertically  and  allowed  to  stand  for  a  short  time.  When 
sufficient  clear  solution  appears,  io  c.c.  of  this  are  taken,  and 
the  consumption  of  cyanide  determined  as  described  on  p.  76. 


80  GOLD   ASSAYING. 

The  solution  is  now  stirred  up  with  about  20  c.c.  of  milk  of 
lime,  and  allowed  to  settle  for  a  few  hours.  The  clear  solution 
is  then  decanted,  the  residue,  mixed  with  clean  water,  stirred, 
allowed  to  settle  and  decanted  as  before,  this  being  repeated 
three  times  to  ensure  complete  extraction.  The  residue  may 


FIG.  60. — CYANIDE  TEST  APPARATUS  FOR  SLIMES. 

then  be  dried  and  assayed ;  and  the  result  deducted  from  the 
amount  found  in  the  original  sample  gives  the  amount  ex- 
tracted, which  should  be  calculated  centesimally.  The  gold  in 
solution  may  be  estimated  by  the  methods  described  on  p.  76. 
This  apparatus  can  also  be  advantageously  used  for  the 
rapid  cyaniding  of  sands  and  for  testing  the  Newberry-Vautin 


ASSAYS   IN   CYANIDATION,   ETC.,   PROCESSES.        8 1 

chlorination  process  on  small  samples  of  ore.     It  can  also  be 
ased  for  amalgamation  assay. 

Where  such  apparatus  is  not  available,  sands  and  slimes 
can  be  cyanided  in  corked  bottles,  giving  them  a  shake 
occasionally. 

Chlorination — Synopsis  of  Process. — The  principle 
of  this  process  is  based  on  the  fact  that  free  gold  is  dissolved 
by  a  solution  of  chlorine  gas,  or  compounds  that  liberate 
nascent  chlorine,  forming  chloride  of  gold,  which  is  soluble. 
Thus— 

Au  +  C13  =  AuCl3 

All  ores  containing  pyrites,  mispickel,  tellurides,  etc.,  are 
first  roasted  before  being  subjected  to  the  process.  Quartz 
and  oxidized  ores  containing  fine  gold  and  no  other  minerals 
can  be  treated  without  previous  roasting. 

The  gold  is  obtained  from  the  filtered  chloride  by  precipita- 
tion with  sulphate  of  iron  or  charcoal,  or  as  an  electrolytical 
deposit,  from  which  it  is  smelted  and  refined  by  usual  methods. 
There  are  numerous  chlorination  processes  in  vogue,  all  of 
which  have  for  their  object  the  conversion  of  the  gold  into 
chloride,  and  the  subsequent  reduction  of  the  chloride  into 
metallic  gold.  For  a  full  description  of  these,  the  reader  is 
referred  to  the  large  manuals  on  Metallurgy. 

Chlorination  Assay. — This  can  be  conveniently  carried 
out  by  the  apparatus  seen  in  Fig.  61,  which  consists  of  a 
flask,  A,  for  generating  chlorine  gas ;  d,  a  wash-bottle  containing 
water,  which  serves  to  wash  the  gas  free  from  hydrochloric  acid. 
C  is  a  glass  cylinder  in  which  the  ore  is  chlorinated ;  D  is  a 
cylinder  containing  rolls  of  blotting-paper  or  shavings  moistened 
with  alcohol,  which  serve  to  absorb  the  excess  of  chlorine 
that  escapes.  The  method  is  conducted  as  follows :  20  ozs. 
of  ore,  previously  roasted  free  from  sulphides,  arsenides,  etc., 
are  weighed.  Into  the  generating  flask  A  place  a  mixture 
of  i  oz.  of  peroxide  of  manganese  in  powder,  4  ozs.  of 

G 


82 


GOLD   ASSAYING. 


hydrochloric  acid,  and  i  oz.  of  sulphuric  acid  previously 
mixed  with  i  oz.  of  water.  Into  the  glass  cylinder  C,  which 
is  8  to  10  inches  high  and  2\  inches  wide,  is  introduced  frag- 
ments of  bottle  glass  about  the  size  of  hazel  nuts,  the  layer 
being  a  couple  of  inches  high.  Over  this  is  placed  a  thin 
layer  of  coarse  clean  sand,  and  then  a  layer  of  fine  quartz  sand. 
Over  the  top  of  this  now  place  loosely  the  20  grams  of  ore 
previously  moistened  with  water.  The  whole  apparatus  is  now 
coupled  together  with  glass  tubing,  as  seen  in  the  sketch.  The 
cover  for  the  cylinder  C  is  made  of  indiarubber. 

A  gentle   heat  is  now  applied  to  the  flask  A,  when  the 


FIG.  61.— CHLORINATION  ASSAY  APPARATUS. 

greenish  gas  will  pass  through  the  water  in    B   and  fill  the 
cylinder  C. 

The  more  coarse  the  gold,  the  longer  should  it  remain  in 
contact  with  the  gas.  If  roasted  pyrites  are  under  treatment, 
about  i  hour  would  suffice,  but  ores  containing  coarse  gold 
should  remain  in  contact  from  5  to  10  hours.  The  apparatus 
is  uncoupled  and  water  poured  into  the  cylinder  C,  and  the 
clear  solution  containing  the  chloride  of  gold  allowed  to  drain 
through  the  orifice  b  into  another  cylinder,  and  after  several 
washings,  to  ensure  complete  extraction  of  the  gold,  the  solution 
is  mixed  with  a  few  drops  of  hydrochloric  acid,  and  excess  of 
a  strong  solution  of  sulphate  of  iron  (ferrous  sulphate^  or 
copperas),  well  stirred  with  a  glass  rod,  and  allowed  to  stand  for 


."*»•*' 
AMALGAMATION    ASSAY.  83 

some  hours  in  a  warm  place  until  the  gold  is  completely  pre- 
cipitated as  a  dark-brown  powder  and  the  solution  above 
remains  perfectly  clear.  The  solution  is  now  carefully  decanted 
or  syphoned  from  the  precipitated  gold,  and  the  latter  is  stirred 
and  collected  on  a  small  filter  paper  by  means  of  a  wash-bottle 
and  a  feather.  The  filter  and  its  contents  are  now  transferred 
to  a  small  porcelain  crucible.  A  gentle  heat  is  first  applied,  so 
as  to  free  from  moisture,  and  then  carefully  heated  in  a  muffle 
until  all  the  filter  paper  has  burnt  off.  The  residue  is  then 
wrapped  up  in  about  ten  times  its  weight  of  sheet  lead,  and 
cupelled  on  bone  ash  (vide  p.  48),  and  the  button  of  gold 
weighed. 

Amalgamation — Synopsis  of  Process.— By  amalga- 
mation is  meant  the  combination  of  mercury  or  quicksilver 
with  the  gold  and  silver  contained  in  the  ore.  There  are 
various  machines  in  use  on  a  large  scale  for  the  purpose,  the 
principal,  however,  being  the  stamp  battery.  Here  the  ore  is 
ground  to  powder,  wet,  and  the  pulp  passes  over  inclined 
copper  plates  amalgamated  with  mercury,  in  which  the  gold 
is  absorbed,  and  from  which  it  is  recovered  by  first  scraping 
off  the  gold  amalgam,  squeezing  out  excess  of  mercury  through 
chamois  leather.  The  resulting  gold  amalgam — which  contains 
from  30  to  40  per  cent,  of  gold — is  retorted,  the  mercury  being 
distilled  and  the  gold  left  in  a  porous  mass,  this  being  eventually 
smelted  with  fluxes  in  plumbago  crucibles  and  cast  into  bars. 

Other  methods  of  amalgamation  consist  in  grinding  the  ore 
wet  in  contact  with  mercury  in  grinding-pans,  of  which  there  is 
a  great  variety. 

Amalgamation  Assay.— When  it  is  necessary  to  ascer- 
tain the  amount  of  gold  that  can  be  extracted  by  mercury  on 
a  small  scale,  the  writer  has  found  that  the  apparatus  shown  in 
Fig.  62  is  very  suitable  for  the  purpose.  As  will  be  observed, 
it  consists  of  an  amalgamator  which  can  be  driven  by  water- 
power  or  by  hand.  The  mortar  in  which  the  amalgamation 
takes  place  is  made  of  iron,  as  is  also  the  grinder,  which  is 


84 


GOLD   ASSAYING. 


arranged  to  revolve.  The  following  is  the  method  of  con- 
ducting the  assay :  1000  grams  of  the  powdered  ore,  about 
1500  c.c.  of  water  made  alkaline  with  caustic  soda,  and  about 
100  grams  of  redistilled  mercury,  are  introduced  into  the 
amalgamator,  the  grinder  of  which  is  made  to  revolve  by 
turning  on  water  to  the  motor.  The  rate  at  which  the 
apparatus  revolves  can  be  regulated  by  the  inflow  of  water. 


FIG.  62.— AMALGAMATION  ASSAY  APPARATUS. 


After  the  apparatus  has  been  running  for  a  couple  of  hours, 
the  motor  is  stopped,  and  the  whole  of  the  contents  washed 
out  into  a  shallow  dish.  The  whole  is  stirred,  and  the  pulp 
carefully  run  off,  leaving  the  amalgam  behind.  Several  wash- 
ings with  water  will,  of  course,  be  required  to  free  all  the  ore 
from  the  amalgam.  The  latter  is  carefully  run  into  a  piece  of 
chamois  leather  held  in  the  palm  of  the  hand.  The  ends  of 
the  leather  are  held  up  together  so  as  to  form  a  bag,  as  it  were. 
These  are  screwed  around  with  the  right  hand,  while  the  left  is 
used  to  squeeze  out  the  excess  of  mercury,  leaving  a  hard 
amalgam  behind.  This  is  transferred  to  a  piece  of  lead-foil 


AMALGAMATION   ASSAY.  85 

about  ten  times  the  weight  of  the  amalgam,  in  which  it  is 
wrapped,  placed  on  a  cupel  transferred  to  a  muffle  furnace,  a 
very  low  heat  being  first  applied  to  evaporate  off  the  mercury, 
otherwise  loss  would  occur  by  spurting.  It  is  then  heated 
more  strongly,  and  the  rest  of  the  process  conducted  as 
described  on  p.  53.  The  amount  of  gold  per  ton  can  be 
calculated  from  the  table  on  p.  55.  As  there  were  1000  grams 
taken,  the  result  as  obtained  from  the  table  must  be  multiplied 
by  20. 

As  a  check  against  the  result,  the  pulp  separated  from 
the  amalgam  could  be  evaporated  to  dryness  and  TOO  grams 
of  this  taken  for  assay  in  the  usual  manner,  and  the  result 
thus  obtained  deducted  from  the  assay  of  the  original  ore 
should  tally  with  that  obtained  from  the  amalgam. 


APPENDIX. 


COINAGE,  VALUATION  TABLES,  MINT  AND 

MINE  STATISTICS,  WEIGHTS  AND  MEASURES, 

ETC.,  ETC. 

The  Imperial  Coinage. 

STANDARD  gold  contains  eleven-twelfths  of  fine  metal,  and  one- 
twelfth  of  alloy.  Twenty  pounds  troy  of  standard  gold  are  coined 
into  934  sovereigns  and  one  half-sovereign  :  i  oz.  troy  is,  therefore, 
intrinsically  worth  .£3  17^.  lo^d.  On  the  same  basis,  i  oz.  of  pure 
gold  is  worth  ^4  4^.  n^d. 

Standard  silver  contains  thirtyseven-fortieths  of  fine  metal,  and 
three-fortieths  of  alloy. 

Bronze  is  an  alloy  of  copper  95  parts,  tin  4  parts,  and  zinc 
i  part. 

The  coinage  of  the  United  Kingdom  consists  of  the  following 
pieces.  Some  of  these  are,  however,  only  issued  from  time  to  time 
on  special  occasions. 

The  Bank  of  England  issues  notes  for  sums  of  £5,  £10,  ^20, 
^50,  ;£ioo,  ^200,  ^500,  and  ^1000. 

The  tender  of  Bank  of  England  notes  is  legal  in  England  and 
Wales  for  all  purposes,  and  by  any  one  except  by  the  Bank  of 
England.  No  one  can  be  compelled  to  give  change. 

Gold  is  a  legal  tender  to  any  amount. 

Silver  is  not  a  legal  tender  for  sums  over  £2. 

Pennies,  halfpence,  or  farthings  are  not  legal  tender  for  sums 
over  is. 

MONEY  TABLE. 

4  farthings,  or  2  halfpennies  =  i  penny  (d.} 
12  pence  .  .  .  .  =  i  shilling  (s.) 
20  shillings  .  .  .  .  =  i  pound  (£) 

\d.  —  i  farthing 
\d.  =  2  farthings 
^d.  =  3  farthings 


90  APPENDIX. 

PROPOSED  DECIMAL  COINAGE. 

i  mil =  .£0-001  =  f  i  q. 

10  mils  =       i  cent      .         .         .  =  ^o'oi     =  2*4^. 

100     „     =     10  cents  =    i  florin  =  £'i        =  2s. 

1000     „     =  100     „      =  10  florins  =  .£1 

OLD  COINS  FORMERLY  IN  USE. 
Gold. 

Joannes  .  =  36^.  od. 

Moidore  .  =  27 s.  od. 

Jacobus  .  =  25.$-.  od. 

Guinea  .  =  2is.  od. 

Mark  .  =  13^.  \d. 

Half-guinea  =  los.  6d. 

Angel  .  =  los.  od. 

Noble  .  =    6s.  &/. 

Dollar  .  =    4J.  6d. 

Silver. 

Tester        .   =  or.  6d. 
Groat         .  =  os.  ^d. 

OLD  SCOTS  MONEY. 

2  pennies   =  i  bodle     .        .  =  \s.  sterling 
4        „        =i  plack  or  groat  =      \s.      „ 

6        „        =i  bawbee  .        .  =  \s.      „ 

12  „       =i  shilling .        .  =      is.      „ 
20  shillings  =  i  pound    .        .  =  2os.      „ 

13  „  &4d.  =  i  mark      .        .  =  13^.      „ 

To  reduce  Scots  money  to  Imperial  values,  divide  by  12. 
The  Irish  pound  (£i)  =  £{%  sterling. 


THE   IMPERIAL   COINAGE. 


91 


BRITISH  COINS  IN  USE,  WITH  THEIR  EQUIVALENTS. 


£5- 

fr 

*. 

«.       5,- 

*  ~.«|~ 

IJ. 

c</.    3</.  id. 

M 

Gold. 

\        . 

v^5>  or  X'5~piece  .          i 

£2,  or  ^2-piece  :         2£        i 

j 

j£l,  or  sovereign, 

or  pound  ..52 

I 

IOJ.,      or       half- 

i 

sovereign  . 

10 

4 

2 

I 

I 

Silver. 

Crown 

20             8 

4 

2           I 

Double  florin 

25        10 

5 

--      1} 

I 

Half-crown  . 

40        1  6 

8 

4         2 

l3 

I 

Florin  . 

SO           20 

10 

5           2* 

2 

I* 

I 

Shilling        .         .      100        40 

20 

10       5 

4 

2| 

2 

I 

Sixpence      .         .     200        80 

40 

20         10 

8 

5 

4 

2 

I 

Threepenny-piece      400       160 

80 

40        20 

16 

10 

8 

4 

2       I 

Copper. 

Penny  .         .         .    1200      480 
Halfpenny    .         .    2400      960 

240 
480 

120        60 
240      1  2O 

48 
96 

30 
60 

24     12 
48    24 

6     3 

12       6 

I 
2 

I 

Farthing      .         .   4800 

1920 

960 

480     240 

192 

120 

96    48 

24    12     4     2 

I 

TABLE  SHOWING  THE  WEIGHT  OF  NEW  COINS. 

A  sovereign,  or  pound,  weighs  123*274  grains 
A  half-sovereign  ,.         61-637       „ 

A  half-crown  „       218-1818     „ 

A  shilling  „         87-2727     „ 

A  sixpence  „         43*6364    „ 


MEASUREMENT  AND  WEIGHT  OF  BRONZE  COINS. 

A  halfpenny  measures  exactly  i  inch  in  diameter,  so  that 
twelve  of  them  in  a  row  make  i  foot. 

In  the  bronze  coinage  three  pence,  five  halfpence,  or  ten 
farthings  weigh  i  oz.  avoirdupois. 


APPENDIX. 


TABLE  OF  VALUES  OF  GOLD. 

Calculated  from  the  standard  at  ,£3  17^.  io^d.  per  ounce. 


Carats  fine. 

Value. 

Carats  fine. 

Value. 

Carats  fine. 

Value. 

£     s.     d. 

£     s.     d. 

£     s.     d. 

I 

o    3    6J 

9 

I    II    IOJ 

17 

302 

2 

071               10 

1    '5     4f 

18 

3    3    8£ 

3 

o  10    7|            ii 

i  18  iij 

19 

3    7    3 

4 

0    14      2                   12 

225! 

2O 

3  Io    9l 

5 

o  17    8J            13           260 

21 

3  14    4 

6 

I       I      2f                I4 

2      9      6J                 22 

3  17  ioi 

I 

i     4    9* 
i     8    3f 

15 
16 

2    13       I 

2  16    7J 

23 
24 

4     i     5 
4    4  1*2 

All  articles  manufactured  of  gold  and  silver,  except  watch- 
cases,  have  to  be  taken  to  the  Assay  Office  of  the  district,  and  if 
found  of  legal  quality  are  stamped  thus — 

The  Hall  Mark,  showing  the  district  where  manufactured,  or 
the  hall  where  assayed,  is,  at  Birmingham,  an  anchor  ;  Chester, 
three  wheat-sheaves  or  a  dagger ;  Dublin,  a  harp  or  figure  of 
Hibernia  ;  Edinburgh,  a  thistle,  or  castle  and  lion ;  Exeter,  a 
castle  with  two  wings  ;  Glasgow,  a  tree,  and  a  salmon  with  a  ring 
in  its  mouth ;  LONDON,  a  leopard's  head ;  New  castle-on-  Tyne, 
three  castles  ;  Sheffield,  a  crown  ;  York,  five  lions  and  a  cross. 

The  Standard  Mark  for  gold  of  22  carats,  and  silver  of  n  ozs. 
2  dwts.,  is,  for  England,  a  lion  passant ;  for  Edinburgh,  a  thistle  ; 
for  Glasgow,  a  lion  rampant ;  for  Ireland,  a  harp  crowned.  Gold 
of  1 8  carats  fine,  a  crown  and  the  figures  18.  Silver  of  the  new 
standard,  figure  of  Britannia. 

The  Duty  Mark  is  the  head  of  the  sovereign,  and  indicates  that 
the  duty  has  been  paid. 

The  Date  Mark  is  a  letter  of  the  alphabet  placed  in  a  shield. 
The  letter  is  changed  every  year. 


Value  per  dwt. 

Value  per  grain. 

£ 

s. 

d. 

£ 

s. 

d. 

o 

4 

O 

0 

0 

2 

0 

3 

io| 

0 

0 

!lf 

0 

3 

9 

0 

0 

I£ 

0 

3 

71 

0 

0 

T16 

0 

3 

6 

0 

0 

If 

0 

3 

4£ 

0 

0 

'H 

o 

3 

3 

0 

0 

If 

0 

3 

II 

0 

0 

IT% 

0 

3 

0 

0 

0 

1^ 

MONEY  OF  COUNTRIES   USING   METRIC   SYSTEM.      93 
GOLD  VALUATION  TABLE. 

Value  per  oz. 
£  s.  d. 
400 

3  17  6 

3  15  o 

3  12  6 

3  10  o 

3  7  6 

3  5  o 

3  2  6 
300 

Every  rise  or  fall  in  the  value  of  gold  of  one  shilling  per 
ounce  gives  a  difference  of  f  of  a  penny  per  dwt.,  and  ^  of  a  penny 
per  grain. 

Money  of  Foreign  Countries  in  which  the  French 
Metric  System  is  in  Use. 

ALGIERS. 

The  French  coins  are  in  general  use. 

Accounts  are  usually  kept  in  French  money  by  European 

merchants. 

ARGENTINE  REPUBLIC. 
Money  the  same  as  in  Spain. 

Peso,  or  dollar  of  100  centesimos,  about       .   =  4^. 
The  par  of  exchange  (P.  of  E.)  =  5-04  pesos    =  £i 
Accounts  kept  in  dollars. 

The  quintal  =  ioi'4  Ibs. 

The  fanega  =1*5  Imperial  bushels 

AUSTRIA. 
New  monetary  system  since  1892. 

Gold. 

20-crown  piece  =  i6s.  &/. 
10  „  „  =  8s.  4<t. 
Ducat  .  .  =  &y.  od. 


94  APPENDIX. 

Silver. 

Crown       .         .   =  os.  lod. 
Half-crown        .   —   os.  $d. 
(2  crowns  or  krones  =  i  florin.) 

Nickel. 

20-heller  piece     =  os.  o\d. 
i  os.  o^d. 

Bronze. 

2-heller  piece    .   =  os. 
i       „         „       .   =  os. 

The  value  of  the  florin  is  about  11*9  to  12*1  to  the  ,£1,  and  equals 
100  kreutzers. 

BRAZIL. 

Accounts  kept  in  milreis. 
Milreis  =  1000  reis    .   =     2s.  $d. 
lo-milreis  piece  .        .  =   22s.  6d. 
P.  of  E.  =  8'9  milreis    =   2os.  od. 

BELGIUM. 
Gold. 

30  francs     .  =   i6s.  od. 

Silver. 

5  francs    .  =  45-.  od. 

2      „  =   is.  id. 

i  franc          =  os.  q\d. 

50  centimes  =  os.  ^d. 

Nickel. 

20  centimes  =  o^.  2d. 
10        „         =  os.  id. 
5        „          -  os.  o\d. 

Accounts  kept  in  francs. 

The  French  metric  system  is  used,  but  some   of  the  values  are 
differently  expressed,  viz. — 

Aune    for  metre  or  ell 
Litron    „   litre  or  kaunen 
Livre     „  kilogram  or  ponden 


MONEY  OF   COUNTRIES   USING   METRIC   SYSTEM.      95 

BOLIVIA. 

The  boliviano  or  dollar  =  100  centavos   =    is.  qd. 
With  half-bolivianos  in  use. 

CHILI. 
Gold. 


£ 

s.     d. 

20  peso  =  : 

[  condor 

.  =  4 

3     4 

10      „       = 

i  doblon 

.    =    2 

i     8 

5     i,     = 

i  escudo  . 

.    =     I 

O    10 

Silver. 

Dollar,  or  peso  (nominal)  =  042 

P.  of  E.  =  5  francs  .        .  =  0311^ 

„        =  5-05  pesos       .  =  100 

A  gold  dollar  is  in  circulation. 

FRANCE. 

Gold. 

20  francs  (the  Napoleon  or  Louis)  =    i6s.  od. 
10      „  .....   =     8s.  od. 

5     »  .....   =     4J.  <*/. 

Silver. 


5  francs 

2       „ 

i  franc        = 

100  centimes         .   = 

4s.  od. 
is.  jd. 
os.  vfed. 

50  centimes  . 

20 

about  = 

os.  4|^. 
os.  'id. 

Bronze. 

10  centimes 
5        »        • 

.        .   = 

os.  id. 
os.  o\d. 

GERMANY. 

Gold. 

20  marks   .   =   2os.  od. 

10      „        .   =    IQS.  od. 

5     „        .  =     sj.  od. 


g6  APPENDIX. 

Silver. 

5  marks   .   =      5^.  od. 
3     „        .  =     sj.  od. 

2       „  .    =       2.S1.   O^/, 

i  mark  .  =  is.  od. 
50  pfennige  =  os.  6d. 
20  „  =  or.  2^. 

Nickel. 

20  pfennige   =  os.  2\d. 

10        ,,         =  os.  i^d. 

5         „         =  os.  o\d. 

Other  names  are  used  in  the  metric  system,  viz. — 
Strich          for  millimetre 


Neuzoll 

„   centimetre 

Stab 

„   metre 

Kette 

„   decametre 

Konne 

„   litre 

Schoppen 

„   half-litre 

Fass 

„   hectolitre 

Neuloth 

„    decagramme 

Pfund 

„   half-kilogramme 

Certner 

=    loo  Ibs. 

Tonne 

=    looo  kilogrammes 

GREECE. 

Gold. 
2o-drachmai  piece   =    14^.  2\d. 

5  »     =    3-y-  ¥• 

Silver. 

i  drachma  .         .   =     os.  qd. 
|         „         .         .   =     os.  ^\d. 
i        .,         .         .   =     os.  2%d. 

Accounts  kept  in  drachma!  and  lepti. 

100  lepti  =    i  drachma 
P.  of  E.  =  25-22  drachmai  =  2OJ. 


MONEY  OF  COUNTRIES   USING  METRIC  SYSTEM.      97 
The  weights  and  measures  of  the  metric  system  have  different 


names — 

Gramne        for  millimetre 


Dactylos 

„   centimetre 

Palame 

„    decimetre 

Pecheus 

„   metre 

Stadion 

,,   kilometre 

Skoinis 

„   myriametre 

Stremma 

),   are 

Kybos 

„  millilitre 

Mystron 

„   centilitre 

Kotylos 

„   decilitre 

Litra 

„   litre 

Koilon 

„   hectolitre 

Kokkos 

„   centigramme 

Obolos 

„  decigramme 

Drachme 

„   gramme 

The  ocque 

=  2-84  Ibs.  (av.) 

The  livre 

=  nib.  (av.) 

The  quintal   =  123-2  Ibs.  (av.) 


HOLLAND. 

Gold. 

10  guilders   = 

i6s.  od. 

Silver. 

2\  guilders           .   = 

4J.  2d. 

i       „ 

is.  M. 

50  cents       .        .   = 

os.  lod. 

25      „          • 

os.  $d. 

10        „ 

OS.  7.d. 

5     »         • 

os.  id. 

Copper. 

5  cents  =  i  stiver    =     os.  id. 
Accounts  kept  in  florins  or  guilders  =  100  cents 


98  APPENDIX. 

The  weights  and  measures  have  different  names,  viz.- 
Length. 

Streep  for  millimetre 
Duim     „   centimetre 
Palm     „   decimetre 
Ell         „    metre 
Roede   „   decametre 
Mijle     „   kilometre 

Capacity. 

Vingerhoed  for  centilitre 
Maatje          „   decilitre 
Kan  „   litre 

Vat  „   hectolitre 

Dry  Measure. 

Maatje  for  decilitre 

Kop  „   litre 

Schepel  „  decalitre 

Mudde,  or  zak   „   hectolitre 

The  last  =  30  mudde 
Weight. 

Korrel  for  decigramme 
Wigtje   >j   gramme 
Lood      „   decagramme 
Ons        „    hectogramme 
Pond      „   kilogramme 

The  bunder  =  i  hectare 
Apothecaries'  weights  are  similar  to  those  of  England. 

ITALY. 

The  same  as  in  France,  but  the  money  in  general  use  is  a  paper 

currency. 

2o-lire  piece      .        .   =   i$s.  lod. 
i  lire  —  loo  centimes   =     os.  q\d. 

The  rate  of  exchange  varies  from  26*2  to  26'$  lires  =  £i. 
Notes  issued  by  local  banks  are  only  payable  at  those  banks. 


MONEY  OF  COUNTRIES   USING   METRIC   SYSTEM.      99 

Weights  and  Measures. 

The  gramma     .  =  I5'43  grains  troy 
Chilo  gramma  .   =  2*2  Ibs.  avoirdupois 
Quintale  metrico  =  220  Ibs.        „ 
Tonnellata         .   =  2200  Ibs.      „ 
Litro  .        .        .   =  0-22  gallons 
Metro         .        .  =  3*28  feet  —  39*37  inches 
Metro  cubo        .  =  35*31  cubic  feet 
Ettara        .        .  =  2*47  acres 

MEXICO. 

Gold. 

£    s.    d. 

Doubloon          .        .        .   =  348 
Half-doubloon  .        .  =    i   12    4 

Silver. 

Dollar,  or  peso,  or  8  reals  =  042 
Half-dollar       .        .        .   =  021 

Accounts  kept  in  dollars  and  cents. 

loo  cents  =  i  dollar 
P.  of  E.  =  4-64  dollars      .   =   i     o     o 


NORWAY  AND  SWEDEN. 


Gold. 

20  kroners 

.    =    22S.   $d. 

10      „ 

.  =   iis.  \\d. 

5      » 

.  =     5J.  6f*T. 

Silver. 

2  kroners 

.   =     2s.  $d. 

i  kroner 

.  =     is.  \\d. 

50  ores 

.  =     os.  6|^. 

25     „ 

.   =     os.  T>d. 

10       „ 

.   =     os.  id. 

IOO  APPENDIX. 

Copper. 

5  ores          .        .   =     oj. 
Accounts  kept  in  crowns, 
i  crown  =  loo  ores    .   =     u.  i\d. 
P.  ofE.  =  i8'2  crowns  =   20^.  od. 

The  coins  of  the  two  countries  pass  freely  between  them,  but  notes 
are  negotiable  in  their  own  country. 

PORTUGAL. 

Gold. 

£  J.    d. 

Johannes  d'or  =  1 2,800  reis     .        .   =   311      o 
Crown =   134 

Silver. 

Dollar  (milreis)       .        .        .        .  =  042 

Cruzada  (with  halves  and  quarters)  =  023 

i  testoon  =  loo  reis        .        .        .  =  005^ 

Copper. 
25  reis     .        .        .        .        .        .   =  o    o      ij 

Accounts  kept  in  milreis  and  reis. 
looo  reis  =  i  milreis 

ROUMANIA. 

The  ley  =  the  franc 

Silver  legal  up  to  50  ley. 

The  gold  coins  are  20,  10,  and  5-ley  pieces  =  i6s..  Ss.,  and  4.9. 

SERVIA. 
The  dinar  =  i  franc 

Gold. 
20  and  10  dinars  =  i6s.  and  8s. 

Silver. 
2  and  i  dinars  =  is.  jd.  and  9}. 

Copper. 
10  and  5  paras  =  id.  and  \d. 


MONEY  OF  COUNTRIES  USING  METRIC  SYSTEM.     IOI 

SPAIN. 

Gold. 

25  pesetas         .        .        .  =   2oj.  od. 
20      „         or  pistole         .  =   i6s.  od. 

Silver. 

1  dollar   .        .        .        .  =     4^.  od. 
5  pesetas         .        .        .  =     $s.  ^d. 

2  „        .         .         .        .   =      is.  4d. 
i  peseta  =  100  centesimos  =     os.  Sd. 

50  cents =     os.  ^d. 

Bronze. 

10  cents    .        .        .        .   =     os.  id. 
5     „        .        .        .        .   =     os.  o\d. 

Accounts  kept  in  pesetas. 

SWITZERLAND. 
No  gold  coin. 

Silver. 

5  francs    .   =  4^.  od. 

2      „        .   =   is.  7d. 

i  franc      .   =  ay. 

50  centimes  =  os. 

Nickel. 

20  centimes  =  os.  2d. 
10        „         =  of.  id. 
5        „  O.T.  o\d. 

Accounts  kept  in  francs  and  centimes. 
100  centimes  =  i  franc,  as  in  France. 

URUGUAY. 
Peso,  or  dollar  =  100  centenas 

VENEZUELA. 
Bolivia  =  i  franc 


102  APPENDIX. 


Weights,  Measures,  and  Money  of  Greater  Britain. 

Imperial  weights  and  measures  are  now  legally  in  force  in  the 
following  colonies,  etc.  : — 

Antigua  New  Brunswick 

Barbadoes  New  South  Wales 

Bermuda  New  Zealand 

British  Guiana  Nova  Scotia 

British  Honduras  Queensland 

Canada  Sierra  Leone 

Cape  of  Good  Hope  Singapore 

Ceylon  South  Australia 

Cyprus  St.  Christopher 

Dominica  St.  Helena 

Fiji  St.  Vincent 

Grenada  Tobago 

Hong  Kong  Trinidad 

Jamaica  Vancouver's  Island 

Malta  Victoria 

Natal  Western  Australia 
Nevis 

BARBADOES. 

Pound  .        .  =  i4s.  $d. 

Crown  .        .  =  5-r.  od. 

Dollar  .        .  =  4s.  6d. 

Shilling         .  =  os.  8ii^. 

2  halfpennies  =  os.  id. 

BRITISH  GUIANA. 

British  gold  and  silver  coin  with  a  small  circulation  of  guilders, 
half-guilders,  and  bits. 

CANADA. 

The  British  and  United  States  coinage  are  both  in  general  use. 

Accounts  kept  in  dollars  and  cents,  of  which 
loo  cents  =  i  dollar  =  4^.  2d. 


WEIGHTS,  MEASURES,  ETC.,  OF  GREATER  BRITAIN.     IO3 

Formerly  accounts  were  kept  in  £  s.  d. — 

£\  currency  =  about  i6s.  8d.  sterling 
£i  sterling    =  about  £i  4^-.  $d.  currency 
P.  of  E.          =4  dollars  86|  cents   =  £i 

CAPE  OF  GOOD  HOPE. 

British  money  is  exclusively  used. 
Old  Dutch  weights  and  measures  are  still  used  in  many  parts. 

Leagner    =  128  gallons 
Half-aum  =  15^      „ 
Muid          =    3  bushels 

CEYLON. 

The  money  is  the  rupee  of  British  India,  with  cent  in  place  of 

annas  and  pies  ;  thus  Ceylon  has  a  decimal  coinage. 
The  measure  of  length  and  surface  are  the  same  as  in  England. 

The  parrah  =  5*62  gallons 
The  seer      =  i  quart 
The  candy  =  500  Ibs.  (av.) 

CYPRUS. 

English,  Turkish,  and  French  gold    and   English   silver,  Cyprus 
piastres,  with  half  and  quarter  pieces. 
9  piastres  =  is. 

GIBRALTAR. 
The  legal  currency  is  that  of  Spain. 

The  peseta  =  i  franc 

25  pesetas,  nominally       .        .        .        .   =  £i 
But  P.  of  E.  is  generally  over  29  pesetas   =  £i 
British  coins  are  also  in  use. 

HONG  KONG. 

The  Mexican  dollar  =  100  cents 
The  Chinese  tael  .   =  10  mace 
ico  candareens      .  =  3^.  %d. 
With  5,  10,  20,  and  5o-cent  pieces. 


104  APPENDIX. 

MALTA. 

Gold. 

£   s.    d. 

Double  louis  .  =  i  18  ij 
Louis  .  .  .  =  o  19  ij 
Half-louis  .  .  =  097-4 

Silver. 

i  pezza,  or  30  tari   =  040 
Scudo          .        .   —  017! 

Accounts  kept  by  the  British  Government  in  British  money. 


MAURITIUS. 
Accounts  kept  in  dollars  and  cents. 

i  dollar     =   4<r.  zd. 
100  cents  =  i  dollar 

Government  accounts  are  all  in  British  money. 

NEW  BRUNSWICK,  NOVA  SCOTIA,  AND  NEWFOUNDLAND. 
Same  as  in  Canada. 

SINGAPORE. 

Accounts  kept  in  dollars  and  cents. 

loo  cents  =  i  dollar   =  45".  id. 
Accounts  are  also  kept  in  rupees,  annas,  and  pies,  as  in  India. 

WEST  INDIA  ISLANDS  (BRITISH). 
Accounts  kept  in  dollars  and  cents. 


WEIGHTS,  MEASURES,  ETC.,  OF  THE  UNITED  STATES.    1 05 

Weights,  Measures,  and  Money  of  the  United  States. 

Gold. 

£    s.    d. 
2o-dollar  piece  =426 


10 

5 

5) 

?'      ~ 

2 
I 

I 

10 

3 
7i 

2\ 

» 

5)            — 

0 

10 

4 

i 

» 

JJ 

0 

4 

2 

Silver. 

i 

dollar 

.   = 

0 

4 

2 

50  cents         .   = 

0 

2 

I 

25 

10 

)i             •   — 
,,   (dime)  = 

0 
0 

I 

0 

5 

5 

j> 

•   = 

o 

o 

zi 

Nickel. 

5 

cents 

-  = 

0 

0 

2J 

2 

cents 

Copper. 

0 

0 

I 

I 

cent 

.   = 

0 

0 

oi 

Exchange,  i  dollar  =  4^.  Q\d.  to  4^.  2d. 

The  weights  and  measures  are  very  nearly  the  same  as  in  Great 
Britain,  with  the  exception  of  capacity  measure,  where  the  old 
Winchester  gallon  and  bushel  are  used. 

i  wine  gallon  =  0-8331  gallon 
i  ale        „    .   =  1-0169       „ 
i  bushel       .   =  0-9694       „ 

Instead  of  the  hundredweight  the    cental  of  100  Ibs.   is  used, 
consequently  the  ton  =  2000  Ibs. 

Foreign  Countries,  each  having  its  own   System  of 
Money,  Weights,  and  Measures. 

ABYSSINIA. 

A  dollar,  or  23  harfs  =  4^.  o.d. 
A  sequin,  or  2\  dollar   =   9^. 


106  APPENDIX. 

Weights. 

I  wakea  =  400  grains 

i  rottolo  =  4800  grains,  or  10  ozs.  troy 

i  mocha  =  i  oz.  troy 

ARABIA. 

£   J.    d. 

Tomaun  .  .  .  .  =  376 
Sequin  .  .  .  .  =  076 

Dollar  (ij  piastre)  .  .  =  042 
Piastre,  or  80  caveers  .  .  =  035 
Larin  (and  its  subdivisions)  =  o  o  io£ 

i  noosfia  =  i  quart 
I  gudda   =  2  gallons 

Tomand  =  40  kellah  =  168  Ibs.  (av.) 
i  maund  .        .        .   =      3   „ 
i  frazil     .        .         .   =    30  ,, 
i  behar    .         .         .   =  450   „ 

BOLIVIA  REPUBLIC. 

Boliviano,  or  dollar  =  5  francs  =  100  centavos   =   is.  <^d. 

Spanish  weights  and  measures  are  used  along   with  the  French 

metric  system. 
The  marc  =  \  Ib.  (av.) 

BULGARIA. 

The  leva  =  100  stotinki   =  qfcd. 

The  French  metric  weights  and  measures  as  well  as  the  Turkish 

are  used. 

BURMAH. 

Money  same  as  in  China, 
i  pulgat  =  i  inch 
i  tha       =154  inches 
i  tain      =  1069*4  yards 
i  dain     =  2*4  miles 

i  solay     =  i  pint 
i  sali       =  i  gallon 
i  teng     —  i  bushel 


FOREIGN   MONEY,   WEIGHTS,   AND   MEASURES.      IO7 

CHINA. 

10  cash     .        .        .        .  =     os.  of*/, 

i  mace    .        .        .        .  =     os.  j^d. 

i  tael,  or  1000  cash         .  =     5^.  lod. 

P.  of  E.  =  3-07  taels  of  silver  =  2os.  od. 

The  decimal  system  is  used  in  all  the  weights  and  measures. 

i  ts'un    .  .        .  .   =  i -4 1  inches 

i  ch'ih    .  .        .  .   =  14-1      „ 

i  chang.  .        .  .   =  141       „ 

i  yin  .        .  .   =  117*5  feet 

i  ching  .  .        .  .   =  121  sq.  feet 

100  mou  (i  ching) .  .   =  72,600      „ 

i  li         .  .        .  .   =  2115  feet 

i  ho       .  .        .  .  =  2  pints 

i  sheng  .        .  .   =  20  „ 

i  tou      .  .        .  .  =  loo,, 

i  tael     .  .        .  .  =  1-333  ozs-  (av.) 

i  chin,  orchitty(i6taels)  =  1*333  Ibs.  (av.) 

i  picul,  or  tan  (100  chins)  =  133*333  Ibs.  (av.) 


DENMARK. 

The  money  of  Norway  and  Sweden  is  in  circulation  here. 

The  pund  =  100  kvint  =  1000  ort  =  ri  Ib.  (av.) 

The  certner         .        .        .        .  —  100-2 1  Ibs.  (av.) 

„     ship  last        .        .        .        .  =  2  tons 

„    tomme =  i  '029  inches 

„     fod =  1-029  feet 

2  fods =  o'686  yards 

The  cubik  fod  .        .        .  =•  1-09  cubic  feet 


„     tondeland     . 
„     flaske  . 

.   =1*36  acres 

„     pot       ... 
„     tonde  (corn) 
„          „     (coal). 

.   =  0-2126  gallons 
.  =  3-8  bushels 
.   -  4-6775  „ 

IO8  APPENDIX. 

EGYPT. 
Gold. 

50  piastres  =  \  £E.  =    icxr.  -$d. 
100        „      =  i  £E.   =   T.QS.  6d. 

Silver. 

=   2s.  o^d. 
id. 


io  piastres      .        .  = 

25. 

20           „ 

4s. 

i  piastre        .        .  = 

OS. 

2  piastres      .        .   = 

OS. 

Nickel. 

5  milliemes          .  = 

OS. 

2                                     •    = 

OS. 

Copper. 

\  millieme   .        .   = 

OS.   ( 

4              J)               *              •     ~ 

OS.  ( 

i  kirat     =  1*125  inches 
i  dra     .  =  27        „ 
i  gasab    =  3  yards  (nearly) 
i  ardeb    =  4*9  bushels 

(The  ardeb  is  a  variable  quantity.) 

i  kantar  =  99*8  Ibs. 
i  rotl     .   =  i '008  „ 
i  oke    .  =  27      „ 

INDIA. 

Silver. 

1  rupee,  about    .  =    is.  2d. 

8  annas      .       •.  =  os.  yd. 

4      „          .        .  =  os.  $d. 

2  „          .        .  =  os.  lid. 

Bronze. 

\  anna       .        .   =  os. 
.        .  =  os. 


FOREIGN   MONEY,   WEIGHTS,   AND   MEASURES.      109 


Bombay. 

guz 

.   = 

27  inches 

beegah 

.   = 

3927  sq.  yards 

seer 

.   = 

2  Ibs.  (av.) 

maund 

.   = 

28       „ 

candy 

.  = 

560     „ 

Bengal. 

i  moote 

.   = 

3  inches 

i  hanth 

.   = 

18    „ 

I  gUZ 

.   = 

i  yard 

I   COSS 

.  = 

2000  yards 

i  jojun 

.  = 

8000     „ 

i  beegah 

.   = 

1600  sq.  yards 

i      „  (N 

W.P.)  = 

3025 

i  ser 

.  = 

2-2046  Ibs.  (av.) 

i   ,, 

.   = 

17619  pints 

Madras. 

kole,  or 

guz  .   = 

32  inches 

moolum 

.   = 

194     »> 

puddee 

.   = 

2-8852  pints 

marcal 

.   = 

2-8852  gallons 

parah 

.  = 

14-4261     „ 

JAPAN. 

Money  reckoned  and  accounts  kept  as  in  China. 
Gold  coins. 

£  s.  d. 


2o-yen  piece 

10    „      „ 
5      „      „ 

M  )) 

10  rin  =  i  sen  . 
loo  sen  =  i  yen 


3  4 
i  8 
o  10 
8  4 

4  2 
o  o} 
4  2 


1 10  APPENDIX. 


Measures,  etc. 

sung       .  =   ri93i  inches 

shaku     .  =   11*931      „ 

keng      .  =  6  feet 

jo   .        .  =   3*3 14  yards 

ri    .         .  =   2*4  miles 

square  ri  =   5-9552  sq.  miles 

sho         .  =   3- 1  pints 

to   .         .  =   3-703  gallons 

koku       .  =  4*96   bushels 

I  kin          .   =    1-325  Ibs. 
PERU— LIMA. 

Silver. 
Accounts  kept  in  dollars  and  reals. 

i  dollar  =  4s.  3^. 
8  reals      =  i  dollar 

PERSIA. 

(J,  J,  and  i -toman  pieces.) 
35  kerans        .        .   =   209.  od. 
10      „     =i  toman  =  6s.  jd. 

There  are  also  J,  i,  and  2-kran  pieces. 

i  batman    .        .  =  13!  Ibs. 
i  gaz  .         .    =  25  inches 

i  parasang         .   =  4  miles 

RUSSIA. 
Gold. 

Imperial  =  10  roubles        .   =   325-.  2\d. 
Half-imperial     .        .        .  =   i6s.  id. 
Ducat        .        .        .        .   =     9.$-.  3f*/. 

Silver. 

Rouble  =  100  copecks      .   —  3^.  i\d. 

Poltin,  or  half-rouble.        .   —  is.  6%d. 

Polpoltin,  or  quarter-rouble  =  os.  <$\d. 

lo-copeck  piece        .        .    =  os.  -$\d. 


FOREIGN   MONEY,   WEIGHTS,   AND   MEASURES.      Ill 


Accounts  kept  in  roubles  and  copecks,  of  which 
100  copecks       .         .        .         .  =  i  rouble 
P.  of  E.  =  6  roubles  40  copecks  =  2os.  od. 


stopa 

saschen 

verst 

vedro 
pajak 

pood 


=  14  inches 

=  7  feet 

=  1 1 66*66  yards 

=  2704  gallons 
=  1*442  bushels 
=  36*1127  Ibs. 


berkowits  =  360  Ibs. 


TURKEY. 

ioo  piastres  =  i  gold  medjidie  (Turkish  pound,  or  liva)  =  iSs.  orf. 
20        „         =i  silver  medjidie     .        .        .        .        .   =    3^.  ^d. 

i  piastre  of  40  paras =    os.  i\d 

P.  ofE.  =  1 10  piastres =  2os.  od. 

pik          =  27*25  inches 
agatsch  =  3*115  miles 

cantar    =3 1*4  gallons 
almund  =1*152      „ 
killon     =0*912  bushels 
oka         =  2*826  Ibs.  (av.) 
cantur    =  127*3     » 
quintal   =199       „ 


Tables  of  Exchange. 

AMOUNT  OF  FOREIGN  MONEY  THAT  SHOULD  BE  PAID  FOR 
ENGLISH  MONEY. 


English 
money. 

Belgium, 
Bulgaria, 
Chili, 
Congo, 
Free  State, 
Italy, 
Salvador, 
Servia, 
Switzer- 
land, 
Uruguay. 

France 
and 
Algeria, 
Luxem- 
burg, 
Roumania 
Tunis,  anc 
Austria. 

Germany. 

Nether- 
lands and 
Dutch 
East 
Indies. 

Denmark, 
Iceland, 
and 
Danish 
West 
Indies, 
Norway, 
and 
Sweden. 

Portu- 
gal, 
Azores, 
and 
Madeira. 

Egypt. 

United 
States, 
Canada, 
and 
Hawaii. 

r           u? 

. 

. 

^ 

C           D 

t/j 

£    *•    d- 

£      CJ 

8       „• 
rt        C 

1   1 

1  I 

I  i 

1 

ft  1 
II  1 

1   I 

0      0      I 

O      IO 

O      IO 

o    08 

o    05 

o    07 

10 

o    004 

0      02 

002 

0      20 

0      21 

o     17 

0      10 

0    15 

30 

o    008 

o    04 

003 

o    30 

o    31 

o    25 

o    15 

O      ^2 

50 

0      012 

o    06 

004 

o    40 

o    42 

o    34 

o    20 

o    30 

70 

o    016 

o    08 

005 

o    50 

o    52 

o    42 

o    25 

o    37 

90 

0      020 

0      10 

OO6 

o    60 

o    63 

o    51 

o    30 

o    45 

no 

o    024 

0      12 

007 

o    70 

o    73 

o    59 

o    35 

o    52 

130 

o    028 

o    14 

Q    o    8 

o    80 

o    84 

o    68 

o    40 

o    60 

o    032 

o     16 

009 

o    90 

o    94 

o    76 

o    45 

o    68 

170 

o    036 

o    18 

0      0    10 

I      00 

i     05 

o    85 

o    50 

o    75 

190 

o    040 

o    20 

0     0    II 

I      10 

i     15 

o    93 

o    55 

o    83 

200 

o    044 

0      22 

oio 

I     20 

i     26 

I      02 

o    60 

o    90 

220 

o    048 

o    24 

020 

2      50 

2      52 

2      04 

I      20 

i     81 

450 

o    097 

o    49 

030 

3    7o 

3    78 

3    06 

i    81 

2      72 

680 

o    146 

o    73 

040 

5    oo 

5    04 

4    08 

2      41 

3    62 

910 

0      195 

o    97 

050 

6    30 

6    30 

5     10 

3    02 

4    53 

I,  !40 

o    243 

I       22 

060 

7    So 

7    56 

6      12 

3    62 

5    43 

1,370 

o    292 

i    46 

070 

8    80 

8    82 

7     H 

4      22 

6    35 

1,590 

o    341 

i     71 

080 

10      00 

10      08 

8     16 

4    83 

7    25 

1,820 

o    390 

i    95 

090 

ii    30 

n     34 

9     18 

5    43 

8     15 

2,050 

o    438 

2     19 

o  10    o 

12      60 

12      60 

10      20 

6    04 

9    06 

2,280 

o    487 

2    44 

0   II      0 

I3      80 

13    86 

II      22 

6    64 

9    96 

2,510 

o    536 

2    68 

O    12      O 

15     10 

IS       12 

12      24 

7    24 

10    87 

2,740 

o    585 

2      92 

o  13    o 

16    30 

16    38 

13      26 

7    85 

ii     77 

2,970 

o    633 

3     17 

o  14    o 

17    60 

17    64 

14      28 

8    45 

12    68 

3,190 

o    682 

3    41 

o  15    o 

18    90 

18    90 

15      30 

9    06 

13    59 

3.420 

o    73i 

3    65 

o  16    o 

20      10 

20    16 

16    32 

9    66 

14    49 

3,650 

o    780 

3    9° 

o  17    o 
o  18    o 

21      4O 
22      60 

21      42 

22      68 

17    34 
18    36 

10    26 
10    87 

16     31 

3,880 

4,110 

o    828 
o    877 

4     14 

4    38 

o  19    o 

23      90 

23    94 

19    38 

ii     47 

17     21 

4,340 

o    926 

4    63 

100 

25      2O 

25      20 

20      40 

12      08 

18     12 

4,570 

o    975 

4    87 

200 

50      40 

50      40 

4O      8O 

24     16 

36    24 

9,140 

I   950 

9    74 

300 

75    60 

75    60 

6l      20 

36    24 

54    36 

2      925 

14    61 

400 

100      80 

100    80 

81     60 

48    32 

72    48 

1  8,'  280 

3    900 

19    48 

500 

126    oo 

126    oo 

IO2      OO 

60    40 

90    60 

22,850 

4    875 

24    35 

600 

151      20 

151      20 

122      40 

72    48 

108    72 

27,420 

5    850 

29      22 

700 

176    40 

176      40 

142      80 

84  56 

126    84 

31,990 

6    825 

34    09 

800 

20  1     60 

201      60 

163      20 

96   64 

144    96 

36,560 

7    800 

38    96 

900 

226   80 

226      80 

183      60 

108    72 

163    08 

41,130 

8    775 

43    83 

IO     O     O 

252    oo 

252    oo 

204    oo 

120      80 

181     20 

45,700 

9    75o 

48     70 

FOREIGN   MONEY,   WEIGHTS,   AND  MEASURES.      113 


RUPEES  TO  POUNDS,  AND  VICE  VERSA. 


Pence 
per 

rupee. 

Mul 
Rupees  to 
pounds  by 

Pounds  to 
rupees  by 

Pence 
per 
rupee. 

Mul 

Rupees  to 
pounds  by 

Pounds  to 
rupees  by 

12 

0-0500 

20*000 

18 

0-0750 

I3333 

i 

0-05IO 

I9-592 

i 

0*0760 

| 

0*0521 

I9-2OO 

l 

O*O77I 

12-973 

0-053I 

18-824 

| 

0-0781 

I2*800 

13 

0-0542 

18-461 

19 

0-0792 

12-632 

i 

0-0552 

l8*II3 

^ 

0-0802 

12*468 

i 

0*0563 

17777 

i 

0-08I3 

I2*308 

f 

0*0573 

I7-454 

1 

0-0823 

I2-I52 

0*0583 

I7'i43 

20 

0-0833 

12*000 

Hi 

0*0594 

16*842 

i 

0-0844 

II-852 

i 

0*0604 

16-552 

0*0854 

II707 

1 

0-06I5 

16-271               f 

0-0865 

11-566 

15 

0*0625 

16*000               21 

0-0875 

11-429 

0-0635 

15738                    i 

0-0885 

11-294 

| 

0*0646 

15-484 

i 

0-0896 

^ 

0*0656 

15-238 

i 

0-0906 

11-034 

16 

0-0667 

I5*000                22 

0-09I7 

I0*909 

i 

0-0677 

14-769 

i 

0-0927 

10*787 

| 

0-0688 

I4;545 

i 

0-0938 

IO*667 

£ 

0*0698 

f 

0-0948 

!0*549 

17 

0*0708 

14-118 

23 

0-0958 

10-435 

£ 

O'O7I9 

13-913 

i 

0-0969 

10-323 

^ 

0*0729 

13-714 

i 

0-0979 

10-213 

1 

0*0740 

13-521 

1 

0*0990 

10-105 

114 


APPENDIX. 


Royal  Mint  Statistics. 

COINS   STRUCK  AT  THE   ROYAL  MlNT,   LONDON. 

Coinage  of  the  Year  1902. 

IMPERIAL. 


Denomination. 

Number  of  pieces. 

Nominal  value. 

Gold— 
Five-pound  pieces 
Two-pound  pieces 
Sovereigns 
Half-sovereigns 

34,911 
45,807 
4,737,796 
4,244,457 

£            *•    d. 

174,555      o    o 
91,614      o    o 
4,737,796      o    o 
2,122,228     10    o 

Silver  — 
Crowns 
Half-crowns 
Florins 
Shillings  . 
Sixpences 
Fourpences  (Maundy) 
Threepences 
Twopences  (Maundy) 
Pence  (Maundy) 

9,062,971 

256,020 
1,316,008 

2,189,575 
7,809,481 
6,367,378 
10,117 
8,287,060 
14,079 
21,278 

7,126,193    10    0 

64,005      o    o 
164,501      o    o 
218,957     10    o 
390,474      i     o 
159,184      9    o 
168     12    4 
103,588      5    o 
117      6    6 
88     13     2 

Bronze  — 
Pence        .... 
Halfpence 
Farthings  .... 

26,270,996 

26,976,768 
13,672,960 
5,125,120 

1,101,084    17    0 

112,403      4    o 
28,485      6    8 
5,338     13    4 

45,774,848 

146,227      4    0 

Totals 

81,108,815 

8,373,505     11    0 

COLONIAL. 


Denomination. 

Number  of 
pieces. 

Currency 
value. 

Nominal  value. 

CANADA. 

Silver  — 
Fifty  cents 
Twenty-five  cents     . 
Ten  cents 
Five  cents 
Bronze  — 
Cents       .    •     . 

120,000 
464,000 
72O,OOO 
2,120,000 

3,000,000 

6o,OOO 
Il6,000 
72,000 
IO6,OOO 

30,000 

£         s.   d. 
12,500      o    o 
24,166     13    4 
15,000      o    o 
22,083      6    8 

6,250      o    o 

CEYLON. 

Silver  — 
Fifty  cents 
Twenty-five  cents     . 
Ten  cents 

6,424,000 

200,000 
400,000 
1,000,000 

384,000 

Rupees. 
100,000 
IOO,OOO 
ICOjOOO 

80,000      0    0 

6,666     13    4 
6,666     13    4 
6,666     13    4 

CYPRUS. 

Bronze  — 
Quarter  piastres 

1,600,000 

72,000 

300,000 
£ 

IOO 

20,000      0    0 

IOO        O      O 

HONG  KONG. 

Silver— 
Fifty  cents 
Twenty  cents  . 
Ten  cents 
Bronze  — 
Cents       .... 

72,000 

100,000 

250,000 
18,000,000 

5,000,000 

100 

$ 
50,000 
50,000 
1,800,000 

50,000 

100      0    0 

10,416     13    4 
10,416     13    4 
375,000      o    o 

10,416     13     4 

JAMAICA. 

Nickel— 
Pence      . 
Halfpence 
Farthings 

23,350,000 

60,000 
48,000 
144,000 

1,950,000 

£ 

250 

IOO 

150 

406,250      0    0 

250      o    o 

IOO        O      O 

150      o    o 

MALTA. 

Bronze— 
One-third  farthings  . 

252,000 

288,000 

500 

IOO 

500      0    0 

IOO        0      0 

STRAITS  SETTLEMENTS. 
Silver— 
Fifty  cents 
Twenty  cents  . 
Ten  cents 
Five  cents 

288,000 

148,000 
1,105,000 
6,118,735 
1,920,000 

100 

$ 
74,000 
221,000 
611,873-5 
96,000 

100      0    0 

15,416     13    4 
46,041     13    4 
127,473     12  ii 
20,000      o    o 

9,291,735 

1,002,8735 

208,931     19    7 

Totals       . 

41,277,735 

715,881     19    7 

u6 


APPENDIX. 


SUMMARY   FOR    1902. 


Description. 

Number  of  pieces. 

Nominal  value. 

Imperial     .... 
Colonial     .... 

81,108,815 
41,277,735 

£          s.     d. 
8,373.505     ii     o 
715,881     19    7 

Totals      . 

122,386,550 

9,089,387     10    7 

CURRENCY  ISSUES  FROM  THE  ROYAL  MINT,  LONDON. 

The  following  table  gives  a  summary  of  the  currency  issues 
from  the  Royal  Mint  during  recent  years  : — 


Metal. 

1902. 

1901. 

Mean  of  10  years, 
1892-1901. 

Gold       . 
Silver 
Bronze    . 

£ 

6,908,000 
937,202 
148,499 

£ 

2,599,000 
914,201 
120,280 

£ 

6,974,437 
1,207,122 
92,199 

Totals      . 

7,993,701 

3,633,481 

8,273,758 

GOLD  AND  SILVER  IMPORTS  AND  EXPORTS. 

The  following  tables  from  Messrs.  Mocatta  and  Goldsmid's 
Circular  show  the  imports  and  exports  of  gold  and  silver  for  the 
years  1898-1902  :  — 

GOLD. 


Year. 

Imports. 

Exports. 

£ 

£ 

1898 

44,000,000 

35,800,000 

1899 

31,500,000 

21,000,000 

1900 

26,7OO,OOO 

18,800,000 

1901 

20,700,000 

13,500,000 

1902 

2O,5OO,OOO 

15,000,000 

YIELDS  OF  GOLD   FROM   BRITISH   POSSESSIONS.      1 1/ 
SILVER. 


Year. 

Imports. 

Exports. 

£ 

£ 

1898 

15,700,000 

15,500,000 

1899                     13,500,000 

13,400,000 

1900                     13,900,000 

14,100,000 

1901                      I2,2OO,OOO 

11,800,000 

1902                     10,500,000 

10,000,000 

Yields  of  Gold  from  British  Possessions. 

The  following  table  shows  the  yields  and  value  of  gold  from 
various  British  Possessions  for  the  year  1902  :  * — 


Ounces  (Troy). 

Approximate  value. 

£ 

Western  Australia  . 

1,871,037 

7,484,148 

Transvaal       ....              1,718,921 

7,3°i,  501 

Victoria          .... 

765007 

3,062,028 

Queensland    .... 

640,463 

2,720,639 

t  India     

517,639 

1,970,230 

New  Zealand 

508,045 

1,951,433 

British  Columbia    . 

28o,000 

1,120,000 

New  South  Wales          .         .                 270,193 

1,080,773 

Rhodesia        .... 

194,169 

776,676 

British  Guiana 

108,552 

434,208 

Tasmania       .... 

70,996 

283,984 

Totals      . 

6,955,522 

27,985,620 

During  the  year  1902  29,953  tons  of  gold  ore  were  mined  in  the 
United  Kingdom. 

*  Per  favour  of  the  Comptroller-General  of  the  Commercial  Depart- 
ment, Board  of  Trade. 

t  In  India  gold  was  only  extracted  from  mines  in  the  provinces  of 
Burma  and  Mysore  in  1902.  No  account,  it  is  stated,  is  taken  of  the 
small  quantities  of  gold  produced  in  parts  of  Northern  India  from  the 
washings  of  river  sands,  as  no  details  are  available. 


APPENDIX. 


Rand  Gold  Outputs. 

The  London  secretary  of  the  Transvaal  Chamber  of  Mines  has 
obtained  the  following  data  from  Johannesburg.  The  gold  output 
for  October,  1903,  of  the  mines  which  have  so  far  restarted  working 
on  the  Witwatersrand,  amounted  10275,664  ozs.  fine  gold,  and  from 
outside  districts  8880  ozs.  fine  gold.  Total  284,544  ozs.,  valued 
at  ,£1,208,669,  as  against  276,197  ozs.,  valued  at  £1,173,211,  for 
September. 

The  following  table  shows  the  total  Transvaal  gold  output  in 
ounces  month  by  month  since  1898  : — 


1903. 

1902. 

1901. 

1900. 

1899. 

1898. 

ozs. 

ozs. 

ozs. 

ozs. 

ozs. 

ozs. 

January    . 
February  . 

199,279 
196,513 

70,304 

81,405 

z 

80,785 

64,408 

431,010 
425,166 

336,577 
321,238 

March 

217,465 

104,127 

— 

84,546 

464,036 

347,643 

April 

227,871 

119,588 

— 

54-772 

460,349 

353.243 

May 

234,125 

138,602 

7,478 

64,249 

466,452 

365,016 

June 

238,320 

142,780 

19-799 

467,271 

365,  091 

July. 

251,643 

149,179 

25,960 

— 

478,494 

382,006 

August 

271,918 

162,750 

28,225 

— 

482,109 

398,285 

September 

276,197 

170,802 

31,936 

— 

426,556 

408,502 

October    . 

284,544 

181,439 

33-393 

— 

26,904 

423,217 

November 

187,375 

39-075 

— 

65,041 

413-517 

December 

— 

196,023 

52,897 

— 

68,525 

440,674 

Totals 

2,397-875 

1,704,374 

238,743 

348,760 

4,252,813 

4,555,009 

The  decrease  in  the  output  of  recent  years  being  due  to  the 
South  African  War  and  labour  difficulties. 


Returns  from  Australian  Mints. 

The  following  tables  show  the  amount  of  gold  received,  value, 
expenditure  and  revenue,  and  composition  of  gold  received  at  the 
Mints  of  Sydney,  Melbourne,  and  Perth  in  recent  years  : — 


RETURNS   FROM   AUSTRALIAN   MINTS. 


119 


WEIGHT,  VALUE,  AND  MINT  CHARGES. 


SYDNEY.                               MELBOURNE. 

PERTH. 

Aver- 

Aver- 

Aver- 

Period. 

Gross 
weight. 

Value. 

age 
mint 
charge 

Gross 
weight. 

Value. 

age 
mint 
charge 

Gross 
weight. 

age 
,,  ,         :  mint 
Value'      charge 

per 

per 

per 

ounce. 

ounce. 

ounce. 

ozs. 

£ 

d. 

ozs. 

£ 

d. 

ozs. 

£       \    ^ 

1899 
1900 
1901 
1902 

948,743 
1,044,518 

864,634 

796,327 

3,377,761 
3,730,975 
3.039,503 
2,870,753 

1-844  i  1,520,739 
1-732  |  1,158,651 
2-671  |  1,048,239 
2-444  !  1,142,244 

5,834,916 
4.485,955 
4,077,194 
4,470,378 

2-135 
2-118 
2-072 
i  '993 

201,314 
527,822 
827,510 
1,320,618 

732,165  5'666 
1,907,828  3-109 
2,9I9,354  '  3*2" 
4,668,905  2*879 

EXPENDITURE  AND  REVENUE. 


SYDNEY. 
(Annuity  .£15,000.) 


MELBOURNE. 
(Annuity  .£20,000.) 


PERTH. 
(Annuity  £20,000.) 


Expenditure. 

Revenue. 

Expenditure. 

Revenue. 

Expenditure. 

Revenue. 

1899 

1900 

1901 
1902 

£ 
14,488 
14,822 
H,599 
14,933 

s.  d. 
4     5 
ii     6 
7  ii 
5     9 

£ 

15,610 
18,856 

18,211 

15,396 

*.  d. 

4    o 
15     7 
ii     3 
8  10 

£  s.  d. 
17,081  2  7 
15,250  6  8 
15,928  6  10 
15.778  17  i 

£  s. 
25,145  5 
19,624  10 

16,664  12 

16,863  7 

d 
7 
5 

4 
I 

£     s. 

14,209      2 
16,946    14 

16,948     7 

;  19,763  15 

d. 

10 

0 

3 

£ 

4,753 
8,439 
13,603 
23.758 

s.  d. 
8    6 
12     7 
7     4 
15  « 

AVERAGE  COMPOSITION  OF  BULLION  RECEIVED. 


SYDNEY. 

MELBOURNE. 

PERTH. 

Period. 

Gold. 

Silver.    :     Base. 

Gold,     i    Silver. 

Base. 

Gold.    |  Silver. 

Base. 

1899 

834  '4 

113-2          52-4 

903'5     '      57  '7 

38-8 

856-2    ;      94-4 

49'4 

1900 
1901 

835-8 
822-3 

ii3'8           50*4 
127-4           50'3 

911-5           51*8 
9I5V           48-8 

36-7 

35'5 

850-9     '      88'8 
830*5         101*2 

60*3 
68-3 

1902 

839'7 

121-4           38'9      i     921'4           46*8 

832*3              112*0 

120 


APPENDIX. 


WESTERN  AUSTRALIA  ROYAL  MINT— PERTH  BRANCH. 

I.— TOTAL  PRODUCTION  OF  GOLD  IN  WESTERN  AUSTRALIA  SINCE 
ITS  FIRST  DISCOVERY  IN  1886,  AND  DURING  THE  YEAR  1902. 


Situation  of  goldfields 

1886  to  1902.                               1902. 

Production  in  ounces. 

Production  in  ounces. 

Gross 

Estimated 

Gross 

Estimated 

weight. 

ne 
content. 

weight. 

fine 

content. 

(Kimberley 

Within  the  tropics 

Pilbarra     . 
PilbarraWest    . 

235,581 

210,387 

14.432 

12,401 

Ashburton 

Between  24°  and 

IGascoyne  . 

36°  S.  lat.  and 
within  300  miles  ' 

Peak  Hill  . 
Murchison 

1,148,804 

1,020,914 

251,112 

215,776 

of  west  coast 

Yalgoo       .  ^      . 

Murchison  East 

' 

Inland     (between 
250     and     700 
miles  from  west 
coast  and  south 
of  lat.  26°) 

Mount  Margaret 
Coolgardie 
Coolgardie  East 
Coolgardie  N.E. 
Coolgardie  North 
Broad  Arrow     . 

8,350,270 

7,423,699 

1,864,567 

1,602,190 

Yilgarn 

„ 

South-west  coast 

Donnybrook 

849 

757                73 

62 

South  coast 

!  PmUiS  Ri'ver    '. 

j      225,747 

200,827         44.787 

38,48 

Goldfields  generally  .... 

13,212 

11,755           2,471 

2,123 

Total  production    . 

9,974,463    8,868,339 

2,177,442 

1,871,037 

RETURNS   FROM   AUSTRALIAN   MINTS. 


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GOLD  AT  INDIAN  MINTS. 


123 


Gold  at  Indian  Mints. 

The  following  table  shows  the  value  in  rupees  of  the  gold  ten- 
dered during  the  past  three  years  at  the  mints  of  Calcutta  and 
Bombay : — 


Year. 

Calcutta. 

Bombay. 

1899-1900 
1900-1901 
1901-1902 

Rs. 
21,203,239 
38,834,952 
20,433,266 

Rs. 

65,325,755 
41,228,213 
21,295,525 

I24 


APPENDIX. 

Summary  of  the  Coinages 


Country. 

Gold. 

Silver. 

Pieces. 

Value. 

Pieces. 

Value. 

United  Kingdom  * 
India  f          .... 
British  Colonies  and  Depen- 
dencies J  .... 

20,516,250 

£ 

18,537,443 

26,270,996 
62,134,555 

63.964.391 

£ 

1,101,085 
3-423,182 

6,452,402 

Total  (British) 

20,516,250 

18,537,473 

I52.369.942 

10,976,669 

Arabia          .... 
Austria-Hungary 
Belgium       .... 
Bolivia          .... 
Brazil  
Bulgaria       .... 

1,579,641 

2,403,707 
IOO 

1,173-878 
No  re 

1,954,966 
48 
4,388,086 

4.736 
1,510.417 

No  re 
69,803 
92,346 

plete  returns 

No  re 
126,455 
480,000 
180,514 
12,912,619 

58,800 
10,119,000 

turns. 
1,411,186 

1,518,658 

11,778,172 

13.903.554 
21,577,269 
151,019 

1,300,000 

4,632,893 
3-902,399 

turns. 
920,901 
1,066,047 

990,650 

not  received. 
5,004,899 
turns. 
3,194,636 

11,958,711 
68,212,454 

420 
1,380,778 

43.235 
10,187 

475.563 
1,023,168 
2,205,279 
10,068 

45.833 

207,287 
104,236 

71,600 
33.867 

6,286 

212,660 

28,157 

140,635 
6,274,244 

Corea  
Denmark     .... 
Ecuador       .... 
Egypt  
France         .... 
French  Colonies,  etc. 

German  Colonies,  etc. 
Greece          .... 
Holland       .... 
Dutch  Colonies,  etc. 
Italy    

5,920 

Luxemburg. 
Mexico  §      .... 
Morocco       .... 
Norway        .... 
Persia  ..... 
Peru     
Portugal       .... 
Pudakota     .... 
Russia  f       .... 
Siam    ..... 
Spain  
Sweden        .... 
Switzerland  .... 
Turkey         .... 
United  States  §    . 

75.194 
96,139 

Com 

113,810 
600,000 

i87.343 
5-428,551 

Total  (Foreign)     . 

16,578,449 

22,893,868 

161,701,248 

12,274,043 

TOTAL  . 

37,094,699 

41,  43  1.,  341 

314,071,190 

23,250,712 

*  Including  gold  coins  struck  at  the  Australian  Branch  mints. 

J  Inclusive  of  coins  struck  at  Calcutta  and  Bombay  (during  the  financial  year  1901-02), 
and  at  the  "  Mint,"  Birmingham. 


SUMMARY  OF  THE  COINAGES  O>-THE  WORLD,    1902.     125 
of  the  World,  1902. 


Nickel. 

Copper  or  bronze. 

Total. 

Pieces.      Value. 

Pieces.      Value. 

Pieces. 

Value. 

£ 

£ 

£ 

45,774,848   146,227 

92,562,094 

19,784,785 

— 

— 

83,361,130 

71.347 

145.495.685 

3,494,529 

252,000 

500 

22,830,000 

43.831 

87.046,391 

6,496,733 

252,000 

500 

151.965-978 

261,405 

325,104,170 

29,776,047 

_ 

58,800 

420 

10,327,134 
10,500,060 

35.506 
190,001 

62,549,082 
9.947.778 

36,769 
5.970 

74,247,723 
20,274,912 
10,500,060 

2,591.425 
41,476 
190,001 

27,980,168 

742,136 

— 

— 

27,980,168 

742,136 

— 

60,000,000 

40,000 

60,000,000 

40,000 

34,003,060 

104,177 

1,436,200 

880 

36,850,446 

148,292 

— 

— 

7,109,914  1    7,230 

7,109,914 

7,230 

—         — 

— 

1,518,658 

10,  187 

8,000,082  I    10,152 

2,602,773 

1,017 

10,602,855 

11,169 

— 

— 

13,450,000 

32,000 

27,631,879 

2,462,529 

27,751,825 

94,914 

8,550,000  !   14,148 
13.599.384  |    6,799 

22,453.654 
67.566,522 

1.037,364 
6,695,078 

— 

— 

— 

151,019 

10,068 

— 



10,000,000 

8,334 

11,300,000 

54,167 

— 

— 

36,000,000 

29,166 

36,000,000 

29,166 

5,974,242 

59.742 

26,308 

ii 

10,639,363 

271,776 

6,000,920 

31.255 

10,001,000 

10,418 

21,354,919 

1,656,326 

2,000,000 

8,000 

— 

— 

2,000,000 

8,000 

— 

— 





920,901 

71,600 

— 

— 

6,210,000 

5-575 

7.35L24I 

109,245 

21,000,000 

30,000 

— 

21,000,000 

30,000 

— 

— 

— 

— 

1,086,789 

99,172 

— 

— 

1,070,000 

1,189 

1,070,000 

1,189 

~ 

— 

1,000,000 

347 

1,000,000 

347 

— 

— 

— 

— 

5,004,899 

212,660 

—           — 

5,373,410 

5.566 

8,681,856 

160,178 

3,000,000    14,000 

1,450,000 

780 

5,050,000 

494,780 

31,298,779 

326,029 

37,838,200 
86,479,722 

73.477 
180,166 

49,984,254 
191,419,506 

394,626 
19,693,058 

187,836,270  •  1,645,912 

374,694,371 

459,842 

740,810,338 

37,273,665 

1188,088,270 

1,646,412 

526,660,349 

721,247 

1,065,914,508 

67,049,712 

•{•  Financial  year,  1901-02. 

$  Fiscal  year  ended  June  30,  1902. 


126  APPENDIX. 

English  Weights  and  Measures. 

AVOIRDUPOIS  WEIGHT. 

Grains.  Drachms.        Ounces.      Pounds.    Stones.  Qtrs.  Cwts. 


i  dram 

I  OZ. 

i  Ib. 
i  stone 

27-34375 
437-5  =           16 
7,000  =         256  = 
98,000  =      3,584  = 

16 

224  = 

i  quarter  =       196,000  = 

7,168  = 

448  = 

28  = 

2 

I  CWt. 

=      784,000  = 

28,672  = 

1,792  = 

112  = 

8=    4 

i  ton 

=  15,680,000  = 

573,440  = 

35,840  = 

2,240  - 

160  =  80  = 

20 


TROY  WEIGHT. 

Grains.       Carats.        Dwts.      Ozs. 

I  carat  =        3! 

i  pennyweight  =      24  =        7^ 

i  ounce  =    480  =    150    =    20 

i  pound  =  5760  =  1800    =  240  =  12 


APOTHECARY'S  WEIGHT. 

Grains,  or 

minims.     Scruples.  Drams.     Ozs. 

i  scruple  =      20 

I  drachm  =      60  =      3 

i  ounce  =    480  =     24  =    8 

i  pound  =  5760  =  288  =  96  =  12 


TABLE  OF  COMPARISON. 

Avoirdupois.  Troy.                 Apothecary's, 

grains.    Ib.  oz.  dr.  gr.  Ib.  oz.dwt.  gr.     Ib.  oz.  dr.  sc.  gr. 

i  scruple  (apoth.)                  =      20  =  000  20  =000  20     =00010 

i  pennyweight  (troy)            =      24  =  000  24  =0010=00014 

i  drachm  (av.)                       =       27  =  0010  =  0013^  =  00017^ 

i  drachm  (apoth.)                 =      60  =  00     15^  =002  22     =00100 

i  ounce  (av.)                          =     417  =  0100  =00  18     5!  =  00701! 

i  ounce  (troy  and  apoth.)    =     480  =  o     i     i  15^  =o    i     oo     =o    i    ooo 

i  pound  (troy  and  apoth.)  =  5760  =  o  13    2  17^  =i     000=1     oooo 

i  pound  (av.)                         =  7000  =1000  =121116=12420 


ENGLISH   WEIGHTS  AND   MEASURES.  127 

MEASURE  OF  LENGTH. 

Rods, 
poles,  or 


Inches. 

Links. 

Feel.        Yards,  perches.  Chns.  Furs. 

i  link 

7-92 

i  foot 

= 

12 

r5l5 

i  yard 

,  = 

36 

=          4-545  = 

3 

i  rod,pole, 
or  perch 

}- 

I98 

=     25        = 

i6J  = 

5* 

i  chain 

= 

792 

=      100            = 

66  = 

22 

=     4 

i  furlong 

= 

7,920 

=   1000             = 

660  = 

220 

=  40  = 

10 

i  mile 

= 

63,360 

=  8000 

5280  = 

1760 

=  320  = 

80  =  8 

SPECIAL  MEASURE  OF  LENGTH. 

6  feet  =  i  fathom 

6082*66  feet  =  i  nautical  mile  or  knot 
3  nautical  miles  =  i  league 
60  nautical  miles,  or  )  _       , 
69-121  English  miles  j  ~ 

360  degrees  =  the  earth's  circuit 


SURFACE  OR  SQUARE  MEASURE. 

Sq.  rods,  Sq.        Sq.         Sq. 
poles,  or   chns.     roods,     acrs. 
Sq.  ins.          Sq.  ft.  Sq.  yds.          perches. 

I  sq.  foot    =  144 

i  sq.  yard  =        1,296=          9 
isq.rod,] 

pole,  or>  =      39,204=    272}=  3oJ 

perch     J 

I  sq.  chain=    627,264=  4,356=  484=          16 

i  sq.  rood  =1,568,160=10,890=         1,210=          40=       z\ 
i  sq.  acre  =6,272,640=43,560=        4,840=         160=     10  =    4 
I  sq.  mile   =         ...  ...    =3,097,600=102,400=64002560  =  640 


128  APPENDIX. 

MEASURES  OF  CAPACITY. 

Solid  Measure. 

1728  cubic  inches  =  i  cubic  foot 
27  cubic  feet      =  i  cubic  yard 
13      „      „         =  i  ton  of  solid  quartz 
23      „       „         =i  ton  of  broken  quartz 
40      „      „         =i  ton  rough  timber 

4°i  »  >  —  I  ton  coal 

42  „  „  =i  ton  of  shipping 

48  „  „  =i  ton  Admiralty  measure 

50  „  „  =i  ton  firewood 

52  „  ,,  =i  ton  hewn  timber 

128  „  „  =i  cord  firewood 

Liquid  and  Corn  Measure. 

Gills.          Pints.   Quarts.  Gallons.  Pecks.  Bushels. 

i  pint        =        4 

i  quart      =         8=2 

i  gallon    =       32  =       8  =      4 

i  peck       =      64  -     16  -       8=2 

i  bushel    =     2-56  =    64  =    32  =     8  =    4 

i  quarter  =  2048  =  512  =  256  =  64  =  32  =  8 

VARIOUS  CONSTANTS. 

gallon       .        .  =  277-276  cubic  inches 

pint  .        .        .  =    34'659  » 

fluid  ounce        .   =      17329          „ 

litre  .        .        .  =    61-02705        „ 

cubic  centimetre  =      0*06102705  „ 

cubic  inch         .  =    16*386176  cubic  centimetres 

i  cubic  inch  of  distilled  water  in  air  at  62°  F.  =  252-336  grains 
i          „  „  „    in  vacuo  at  62°  F.  =  252*645      „ 

i  minim  is  the  volume  of  0-91  grain  of  water 

i  fluid  drachm      „      of  54-68  grains  of  water 

i  fluid  ounce         „      of  437-5        „         „ 

i  gallon  is  the       „      of  10  Ibs.  or  70,000  grains  of  water. 


WEIGHTS,    ETC.,  OF    BRITISH    PHARMACOPOEIA.       1 29 


Weights  and  Measures  of  the  British  Pharmacopoeia 
of  1867. 

WEIGHTS. 

i  grain  (gr.) 

•    i  ounce  (oz.)  =    437*5  grains 

i  pound  (Ib.)  =  1 6  ozs.  =  7000        „ 


MEASURES  OF  CAPACITY. 

i  minim  (min.) 

i  fluid  drachm  (fl.  drm.)  =  60  minims 

i  fluid  ounce  (fl.  oz.)        =    8  fluid  drachms 

i  pint  (O)  =  20  fluid  ounces 

i  gallon  (C)  =8  pints 


MEASURES  OF  LENGTH. 
/ 
i  line  =  jV  inch 

i  inch  = — l- seconds — pendulum 

39' 1 393 

12  inches  =  i  foot 
36      „      =3  feet  =  i  yard 


Weights  and  Measures  of  the  Metrical  System. 
WEIGHTS. 

i  milligram  =  0*001  grm. 

i  centigram  =  o  01      „ 

i  decigram    =  o-i        „ 

i  gram       .  =  weight  of  a  cubic  centimetre  of  water  at  4°  C, 

i  decagram  =       10  grms. 

i  hectogram—     100    „ 

i  kilogram    =  icoo     „ 

K 


130 


APPENDIX. 


MEASURES  OF  CAPACITY. 

i  millilitre  =  i  cubic  centimetre  of  water  at  4°  C. 

i  centilitre  =  10  cubic  centimetres 

i  decilitre  =  100      „            „ 

i  litre          =  1000 


MEASURES  OF  LENGTH. 

i  millimetre  =  ofooi  metre 
i  centimetre  =  0*0 1         „ 
i  decimetre  =  o-i          ,, 

i  metre        =  the  ten-millionth  part  of  a  quarter  of  the  earth's 
meridian  (nearly). 


Tables  for  Conversion  of  Metrical  and  English 

Measures. 
\ 

A.  LENGTH. 
METRICAL  TO  ENGLISH.  ENGLISH  TO  METRICAL. 


(i)  Millimetres  to 
inches. 

(2)  Metres  to  feet. 

(3)  Inches  to  milli- 
metres. 

(4)  Feet  to  metres. 

I  =  0-03937079 
2  =  0*07874158 

I  =     3-2808992 
2  =     6-5617984 

I  =     25-39954 
2  =     50*79908 

I  =  0*30479449 
2  =  0*60958898 

3  =  0-11811237 

3  =    9-8426976 

3  =    76-19862 

3  =  0-91438347 

4  =  0-15748316     4  =  13-1235968 

4  =  101-59816 

4  =  1-21917796 

5  =  0-19685395     5  =  16-4044960 
6  =  0-23622474     6  =  19-6853952 

5  =  126-99770 
6  =  152-39724 

5  =  i'52397245 
6  =  1-82876694 

7  =  0-27559553     7  =  22-9662944 

7  =  177-79678 

7  =  2-13356143 

8  =  0-31496632 

8  =  26-2471936 

8  =  203-19632 

8  =  2-43835592 

9  =  o-354337ii 

9  =  29-5280928 

9  =  228-59586 

9  =  2-74315041 

METRICAL  AND   ENGLISH   MEASURES. 


B.  CAPACITY. 
METRICAL  TO  ENGLISH. 


(i)  Cubic  centimetres 
to  cubic  inches. 

(2)  Litres  to  fluid 
ounces. 

(3)  Litres  to  pints. 

(4)  Litres  to  gallons. 

I  =  0-06102705 
2  =  O'I22O54IO 

3  =  0-18308115 
4  =  0-24410820 
5  =  0-30513525 
6  =  0-36616230 
7  =  0-42718935 
8  =  0-48821640 
9  =  0-54924345 

i  =    35-215468  i  i  =    1-7607734 

2  =      70-430936       2  -     3-5215468 

3  =  105-646404     3  =    5-2823202 
4  =  140-861872  i  4  =    7-0430936 
5  =  176-077340     5  =    8-8038670 
6  =  211-292808  j  6  =  10-5646404 
7  =  246-508276  !  7  =  12-3254138 
8  =  281-723744  :  8  =  14-0861872 
9  =  316-939212     9  =  15*8469606 

i  =  0-22009668 

2  =  0-44019336 

3  =  0-66029004 
4  =  0*88038672 
5  =  1-10048340 
6  =  1-32058008 
7  =  1-54067676 
8  =  1-76077344 
9  =  1-98087012 

ENGLISH  TO  METRICAL. 

(i)  Cubic  inches  to 
cubic  centimetres. 

(2-")  Fluid  ounces  to 
cubic  centimetres. 

(3)  Pints  to  litres. 

(4)  Gallons  to  litres. 

I  =      16-386176 
2  =     32-772352 

3  =    49-158528 
4  =    65-544704 
5  =    81-930880 
6  =    98-317056 
7  =  114-703232 
8  =  131-089408 
9  =  147-475584 

I  =     28-396612 
2  =     56793224 

3  =    85-189856 
4=  113-586448 
5  =  141-983060 
6  =  170-379672 
7  =  198-776284 
8  =  227-172896 
9  =  255-569608 

I  =  0-567932 
2=  1-135864 

3  =  1703796 
4  =  2-271728 
5  =  2-839660 

6  =  3"407592 

7  =  3-975524 
8  =  4-543456 
9  =  5-111388 

I  =     4'543458 
2  =     9-086916 

3  =  13*630374 
4  =  18-173832 
5  =  22-717290 
6  =  27-270748 
7  =  31-804206 
8  =  36-347664 
9  =  40-891122 

C.  WEIGHT. 
METRICAL  TO  ENGLISH. 


(i)  Grams  to  grains. 

(2)  Kilograms  to  ounces. 

(3)  Kilograms  to 
pounds. 

I  =     15-4323488 

I  =     35-27394 

I  =     2-20462 

2  =     30*8646976 

2  =     70-54788 

2  =     4-40924 

3  =    46-2970464 

3  =  105*82182 

3  =   6-61386 

4=    61-7293952 

4=  141-09576 

4=    8-81848 

5  =    77-1617440 
6  =    92-5940928 

5  =  176-36970 
6  =  211-64364 

5  =  11-02310 
6  =  13-22772 

7  =  108-0264416 

7  =  246-91758 

7  =  i5'43234 

8  =  123-4587904 
9=  138-8911392 

8  =  282-19152 
9  =  3  17-46546 

8  =  17-63696 
9  =  19-84158 

132 


APPENDIX. 

ENGLISH  TO  METRICAL. 


(i)  Grains  to 
grams. 

(2)  Ounces  to 
grams. 

(3)  Pounds  to 
kilograms. 

(4)  Hundredweights 
to  kilograms. 

I  =  0*0647989 
2  =  0*1295978 

3  =  0-1943967 
4  =  0-2591956 
5  =  0-3239945 
6  =  0-3887934 

7  =  0-4535923 
8  =  0-5183912 
9  =  0-5831901 

I  =     28-34954 
2  =      56-69908 

3  =    85-04862 
4  =  i  I3'398i6 
5  =  141-74770 
6  =  170-09724 
7  =  198-44678 
8  =  226-79632 
9  =  255-14586 

I  =  0-45359265 
2  =  0*90718530 

3  =  1-36077795 
4  =  1-81437060 
5  =  2-26796325 
6  =  2-72155590 
7  =  3-17514855 
8  =  3-62874120 
9  =  4-08233385 

I  =     50*8023768 
2  =  101-6047536 

3  =  152-4071304 
4  =  203-2095072 
5  =  254-0118840 
6  =  304-8142608 
7  =  355-6166376 
8  =  406-4190144 
9  =457-2213912 

Symbols  and  Atomic  Weights  of  the  Elements. 


Element. 

Symbol. 

Atomic  weight. 

Observer. 

Aluminium 

Al 

27-02 

Mallet. 

Antimony 

Sb 

I20'00 

Schneider,  Cooke. 

Arsenic 

As 

75*15 

Kessler. 

Barium 

Ba 

136-84 

Marignac. 

Bismuth 

Bi 

210-00 

Dumas. 

Boron 

B 

11-04 

Berzelius. 

Bromine 

Br 

79-76 

Stas. 

Cadmium 

Cd 

112-04 

Lenssen. 

Caesium 

Cs 

I33-00 

Bunsen. 

Calcium 

Ca 

39^0 

Erdmann. 

Carbon 

C 

11-97 

Dumas,  Liebig. 

Cerium 

Ce 

I38-24 

Rammelsberg. 

Chlorine 

Cl 

35'37 

Stas. 

Chromium 

Cr 

52-08 

Siewart. 

Cobalt 

Co 

5874 

Russell. 

Copper 

Cu 

63*12 

Millon  and  Commaille. 

Didymium 

D 

142-44 

Hermann. 

Erbium 

E 

168-90 

Bahr  and  Bunsen. 

Fluorine 

F 

18-96 

Luca,  Louyet. 

Gallium 

Ga 

69-80 

Lecoq  de  Boisbaudran. 

SYMBOLS  OF  THE  ELEMENTS. 


133 


SYMBOLS  AND  ATOMIC  WEIGHTS  OF  THE  ELEMENTS— continued. 


Element. 

Symbol. 

Atomic  weight. 

Observer. 

Glucinum 

Gl 

9-30 

Awdejew,  Klatzo. 

Gold 

Au 

19671 

Berzelius. 

Hydrogen 

H 

1*00 

Dulong  and  Berzelius. 

Indium 

In 

II3*40      . 

Winkler,  Bunsen. 

Iodine 

I 

I26-54 

Stas. 

Iridium 

Ir 

196-87 

Berzelius. 

Iron 

Fe 

56*OO 

Dumas. 

Lanthanum 

La 

I39'33 

Hermann. 

Lead 

Pb 

206*40 

Stas. 

Lithium 

Li 

7-00 

Stas. 

Magnesium 

Mg 

23*94 

Dumas. 

Manganese 

Mn 

54*04 

Schneider. 

Mercury 

Hg 

200*00 

Erdmann. 

Molybdenum 

Mo 

96-00 

Dumas,  Debray. 

Nickel 

Ni 

5874 

Russell. 

Niobium 

Nb 

94-00 

Marignac. 

Nitrogen 

N 

14-01 

Stas. 

Osmium 

Os 

199-03 

Berzelius. 

Oxygen 

O 

15-96 

Palladium 

Pd 

106-57 

Berzelius. 

Phosphorus 

P 

30-96 

Schrotter. 

Platinum 

Pt 

i94*38 

Seubert. 

Potassium 

K 

39-04 

Stas. 

Rhodium 

Rh 

104*21 

Berzelius. 

Rubidium 

Rb 

85*40 

Bunsen,  Piccard. 

Ruthenium 

Ru 

104-40 

Berzelius. 

Selenium 

Se 

79*46 

Dumas. 

Silver 

Ag 

107*67 

Stas. 

Silicon 

Si 

28*10 

Dumas. 

Sodium 

Na 

22*99 

Stas. 

Strontium 

Sr 

87*54 

Marignac. 

Sulphur 

S 

31-996 

Stas. 

Tantalum 

Ta 

182-300 

M  arignac. 

Tellurium 

Te 

128*06 

V.  Hauer. 

Thallium 

Tl 

203*66 

Crookes. 

Thorium 

Th 

23  1  '44 

Delafontaine. 

Tin 

Sn 

uS'io 

Dumas. 

Titanium 

Ti 

50*00 

Pierre. 

Tungsten 

W 

184*00 

Schneider,  Roscoe. 

134  APPENDIX. 

SYMBOLS  AND  ATOMIC  WEIGHTS  OF  THE  ELEMENTS— continued. 

Element.  Symbol.  Atomic  weight.             Observer. 

Uranium  U  237*60            Ebelman. 

Vanadium  V  51 '35            Roscoe. 

Yttrium  Y  92*5  5             Bahr  and  Bunsen. 

Zinc  Zn  65*16            Oxel  Erdmann. 

Zirconium  Zr  89*60            Marignac. 


INDEX. 


A  CIDITY  of  gold  ores,  74 
I\    Agate  mortar,  25 
Amalgamation,  83 

apparatus,  84 

assay,  83 
Amalgams,  14 

American  gold,  composition  of,  5 
Analyses  of   West  Australian  tel- 

luride  ores,  8 

Analysis  of  Lake  View  ore,  8 
Apothecary's  Weight,  126 
Appendix,  87 
Assay  balance,  49 

crucible,  34 

flasks,  65 

furnaces,  35 

tables,  55 

Atomic  weights  of  elements,  133 
Auric  chloride,  15 

cyanide,  16 

oxide,  15 

tribromide,  16 
Aurous  chloride,  15 

cyanide,  16 

oxide,  14 

protobromide,  16 

Australasia  gold  returns,  1902,  122 
Australian  mint  returns,  1902,  118 
i  Automatic  cupel  machine,  41 


BALANCE,  assay,  49 
portable,  51 
pulp,  32 

Bank  of  England  notes,  89 
Braun  ore  sample  crusher,  21 
British    coins    in    use,    and    their 

equivalents,  91 
Bromides  of  gold,  16 
Bronze     coins,      dimensions     and 

weights,  91 

Bucking-plate  and  hammer,  27 
Bullion,  assay  of,  59 
Burette,  graduated,  77 


PALAVERITE,  7 

\^     Calkins'  cupel  machine,  41 

gyratory  mortar,  25 
Carat  system,  59 
Central  American  gold,  6 
Charges  for  scorification,  58 

various  ores,  35 

Chemical  properties  of  gold,  13 
Chlorides  of  gold,  15 
Chlorination  assay,  81 

apparatus,  82 

process,  81 

Clarkson's  laboratory  divider,  30 
Coarse  gold,  4 


136 


INDEX. 


Coinage    issues    of   the  world  for 

1902,  124 
Coins  struck  at  Royal  Mint,  1902, 

114 

Constants,  various,  128 
Consumption  of  potassic  cyanide,  76 
Coolgardite,  8 

Copper,  estimation  of,  in  bullion,  63 
Cornet  rolls,  62 
Cornets,  64 

Corrections  necessary  in  assays,  67 
Coruscation,  48 
Crucible  tongs,  35 
Cupel,  40 
Cupel  machine,  automatic,  41 

moulds  (Mint),  40 
Cupellation,  39 

tongs,  48 

Cyanidation  tests,  73 
Cyanide  extraction  test  apparatus, 
80 

process,  73 

test  flask,  77 
Cyanides  of  gold,  16 


DATE  mark,  92 
Decimal  coinage,  proposed,  90 
Decimal  system,  60 
Dendritic  gold,  4 
Duty  mark,  92 


"C  NARGITE,  analysis  of,  9 
.L/     English  weights  and  measures, 

126 

Extraction  tests,  75 
for  slimes,  79 


FERROUS  sulphate  test,  19 
Flake  gold,  2 
Fletcher's  gas  assay  furnace,  36 

gas  muffle  furnace,  45 
Fluxes  for  various  ores,  35* 


Forceps,  33 

Foreign  countries  having  own  sys- 
tem of  coins,  105 

Foreign  money  and  English 
equivalents,  112 

Foreign  money  where  French  sys- 
tem in  vogue,  93 

Forms  of  gold,  2 

Free  gold,  4 

Fulguration,  48 

Fulminate  of  gold,  17 

Furnaces,  assay,  35 

Fusion,  34 


p  EOLOGIST'S  hammers,  23 
\J     Gold  and  copper,  14 
Gold  and  its  combinations,  13 
and  silver,  13 
at  Indian  mints,  123 
buttons  and  cornets,  64 
determination  of,  in  solution, 

76 
in  quartz,  estimation  of  by  sp. 

gr.,  71 

valuation  table,  93 
yields  from  British  possessions, 

117 

Graduated  flask,  77 
Greater  Britain,  weights,  measures, 

and  money,  102 
Gyratory  mortar,  25 


H 


ALL  mark,  92 

Hammer,  metallurgical,  54 


IMPERIAL  coinage, 
1     Ingot  mould,  38 
Introduction,  I 
Iodine  test,  19 
Iron  pyrites,  gold  in,  7 


INDEX. 


137 


TT'ALGOORLITE,  8 


L 


EAD  button,  cupellation  of,  48 
Liquid  and  corn  measure,  128 


TVJE  AS  U  RES  of  capacity,  128 
1V1     Measures  of  length,  127 
Melbourne  Mint  returns,  119 
Metric  system,  129 
Metric  and   English   system   com- 
pared, 131 
Microscopical  determination  of  gold, 

69 
Morgan's  assay  furnace,  36 

muffle  furnace,  44 
Mortars,  23 
Muffle,  41 
Muffle  furnace  :  gas,  45 

Mint,  42 

Morgan's,  44 

oil,  46 

prospector's,  43 
Mustard  gold,  4 


VTAGYAGITE,  7 

1M      Natural  occurrence  of  gold,  2 

Nelson's  oil  assay  furnace,  37 

muffle  furnace,  46 
Nuggets,  5 


OLD  coins  formerly  in  use,  90 
Old  Scots  money,  90 
Origin  of  gold  deposits,  9 
Oxides  of  gold,  14 


DARTING  with  nitric  acid,  53 
1       Perchlorideof  gold,  15 
Perth  (W.  A.)  Mint  returns,  119 
Petzite,  8 
Physical  characters  of  gold,  1 1 


Porcelain  crucible,  54 
Preparation  of  powdered  sample,  30 
Process  of  assay,  61 
Prospector's  muffle  furnace,  43 

set  of  apparatus,  47 
Pulp  balances,  32 
Pure  gold,  preparation  of,  1 7 
Purple  of  Cassius,  17 
Pyritic  ores,  assay  of,  57 


Q 


UARTERING,  29 


RADIAL    bucking  -  plate     and 
hammer,  27 
Rhodic  gold,  4 
Rough  gold,  4 
Royal  Mint  statistics,  114 
Rupees  to  pounds,  113 


SAMPLING  of  gold  ore,  20 
Scorification,  56 
Scorifying  tongs,  56 
Shears,  63 

Siberian  gold,  composition  of,  5 
Sieves,  31 

Silver,  estimation  of,  in  bullion,  64 
Spatula,  32 
Sponge  gold,  4 
Square  measure,  127 
Standard  gold,  89 
Standard  mark,  92 
Stannous  chloride  test,  19 
Sydney  Mint  returns,  1 19 
Sylvanite,  8 


of  comparisons,  weights, 
1      and  measures,  126 
Tables,  carat  and  decimal  equiva 

lents,  6 1 

Tank  capacities,  78 
Telluride  ores  of  gold,  7 


138 


INDEX. 


Tests  for  gold,  18 
Tongs,  crucible,  35 

cupellation,  48 

scorifying,  56 
Troy  weight,  126 

UNITED     STATES,     weights, 
measures,  and  money,  105 

VALUATION   of   gold  sent  to 
mints,  69 
Values  of  gold,  table  of,  92 


WALKER'S     specific     gravity 
balance,  72 
Wash-bottle,  54 
Weighing,  49 
Weights,  assay,  50 
Weights  of  new  coins,  91 

pulp,  33 

Welsh  gold,  composition  of,  6 
West  Australian  gold,  composition 

of,  6 

returns  1886  to  1902,  120 
Wet  assay  of  gold,  68 


THE   END. 


R  A  R 
OF  TH 

UNlVESSiT 

OF 


PRINTED   BY   WILLIAM   CLOWES  AND   SONS,    LIMITED,    LONDON   AND  BECCLES. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 
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JAN  2  8 1963 

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